Operational Obstetrics & Gynecology - 2nd Edition: The Health Care of Women in Military Settings

Medical Support

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Pre-deployment Planning	Menstruation Issues	Host Nation Issues
AMAL Supplementation	Bathing	Pregnancy
Pregnancy Policy	Quarters	STD's and Safe Sex
Pre-deployment Screening	Clothing	Aerospace Medicine
Pre-deployment Briefing	Liberty Risks	Gravitational Forces
Urination Issues	Leadership	Decompression Sickness
		Pregnancy and Aviation

Pre-deployment Planning

Planning for the medical support of women in operational environments is important for a successful operation. Four planning areas are particularly important:

• Supplementation of AMALs (standard equipment and supplies) and Sick Call Blocks to support female personnel
• Establish Command policy on deployment and medical evacuation of pregnant personnel
• Pre-deployment screening of deploying women
• Pre-deployment briefing of all personnel on women's health issues and host nation customs

AMAL and Sick Call Block Supplementation

Knowing your available equipment and supplies is the first step. Perform a line-item review of AMAL contents by category to insure your familiarity with it. Frequently needed additional items include:

• Small size surgical gloves worn by female medical personnel and small males.
• Equipment required for pelvic exams. The need to provide for pelvic exams depends on your proximity to higher echelon operational and fixed MTF's (Medical Treatment Facilities). If a better equipped US Military facility nearby is able to provide this service, you may not need to establish this capability. Maintaining pelvic exam capability requires considerable logistical planning and funding. Do not assume that every higher echelon facility has this capability - check before you deploy.
• Speculums - small and medium. Disposable types are good because the ability to clean and repackage speculums in the field is limited. However, metal instruments may be the only type available and have the advantage of being reusable.
• Light source - You will need some type of light source that can be directed as needed. Goose neck or fiberoptic lights are nice but not always available. Automotive type caged "shop lights" provide excellent operational lighting, can be hung anywhere, and are inexpensive.
• Drapes - Some type of draping for exams should be provided, disposable or fabric. Disposable drapes are rarely available. Bed linens (sheets and blankets) are not included in AMALs. You'll need to obtain these from unit supply. Note: you'll need some means to wash non-disposable linens.
• Microscope - ideally needed to perform wet-preps of vaginal discharge, but this is optional as general clinical guidelines can be used for brief field operations.
• Consumable supplies - normal saline, KOH, microscope slides, coverslips, lens paper, large and small cotton tip applicators, K-Y Jelly, and stool guiaic kit.
• Equipment for early OB care. This capability should be taken into an operational setting only when large numbers (100+) of deployed women are to be supported in a highly isolated setting or when civilian humanitarian operations require.
• An OB "Wheel" is very helpful.
• Tape measure.It is helpful for measuring fundal heights and for assessing any structure that might be enlarging over time, such as masses, cysts, hematomas, etc.
• Fetal Doppler.There is no good substitute for a fetal Doppler. The DeLee stethoscopes are effective after 20 weeks of pregnancy, but require some practice to be proficient. A Doppler is much easier.Remember to bring ultrasonic conductive gel. If you don't have any, any water-soluble lubricant such as K-Y jelly, will serve reasonably well as a sonic conductor. Even water is better than nothing.
• Bedpan. This not only serves the obvious function but provides excellent buttocks elevation for pelvic exams and precipitous deliveries.
• For routine obstetrical care, it is useful to have some forms, including a prenatal risk assessment form and a standard pregnancy form.
• Bring a precipitous delivery package...just in case!
• Prenatal vitamins.
• Iron tablets.
• BCPs.
• Make sure to pack an adequate supply of birth control pills (Lo Ovral is a good, multipurpose BCP). Each deploying woman should bring enough BCPs to last for the entire deployment, but sometimes they get lost or damaged, and sometimes you'll need extra BCPs to treat specific problems such as bleeding, pain, or as emergency contraception.
• Have some antibiotics appropriate for urinary tract infections. Septra, Bactrim and Macrodantin all work well for this. Women have many more UTI's than men and are particularly vulnerable to them in a field environment.
• In addition to antibiotic, having a urinary tract analgesic will enable you to keep your patients with UTI's functional while treating their bladder infection. These turn the urine a vivid red-orange color and this is of clinical significance because:
  • Women who are not aware of the urinary color change caused by these dyes can be very alarmed.
  • Soldiers who are using the color of their urine to monitor their hydration status will be unable to use this method while taking the dye.
• Antifungal medication. Creams such as Monistat or GyneLotrimin work well, but are messy in the field environment. Diflucan tablets (150 mg PO once) are highly effective, take up very little space, but are relatively expensive.
• Women who have frequent yeast infections should bring their personal preference for antifungal medication with them.
• Metronidazole. It is very effective against many enteric infections, trichomonads and bacterial vaginosis (anaerobic vaginal bacterial infections). All of these are common in field situations, making Flagyl very useful.
• Lidocaine cream or gel, for genital herpes outbreaks can relieve discomfort and keep personnel functional.
• Sexual assault kit. These can usually be obtained free from the Naval Criminal Investigative Service. For major or remote deployments take a sexual assault kit even if you do not have pelvic exam capability. It is best not to rely on higher echelons for this.
• Pregnancy test kits. Urine HCG test capability is not included in the laboratory AMALs used by echelons 1 and 2. They are strongly recommended for units deploying with women.
• Urine dipsticks. These are useful for providing information regarding UTI's, renal stones, liver disease and hydration status status.

Command Pregnancy Policy

Establish Command Policy on deployment of pregnant women. Though some of the military services may allow for limited deployment of some pregnant women during early pregnancy, that does not mean it is a good idea for your particular deployment. The reasons for this are many:

• Ectopic pregnancy occurs relatively frequently (about one in one hundred pregnancies or more). Unless intrauterine pregnancy has been demonstrated by ultrasound prior to deployment, the risk of ectopic remains a possibility. Ruptured ectopics are life-threatening emergencies even in ideal circumstances. In isolated settings, they are particularly dangerous.
• One in five pregnancies ends in miscarriage in the 1st trimester. 50% of women with bleeding in the 1st trimester go on to have a miscarriage. Echelon 1 and 2 MTF's are not designed to manage miscarriages and likely will not be able to deliver optimal care for them. Miscarriage management requires the ability to not only perform dilatation and curettage if required, but also to type blood and administer Rhogam if needed.
• General Medical Officers do not typically possess the training and skills to confidently manage early pregnancy problems. Where GMO's have significant training in OB, their decision-making is based on the availability of hospital-type diagnostic information: qualitative and quantitative HCG, progesterone levels, and ultrasounds, none of which are usually available to them in operational settings.
• Many significant clinical care events occur in the first 20 weeks of pregnancy. Early OB patients must be monitored for timely appearance of fetal heart tones with doptone and fetoscope and quickening. They must be offered alpha fetoprotein and other tests within certain gestational windows for optimal management. Operationally deployed women may not have the opportunity to get this time-sensitive care by qualified providers.
• Emergency MEDEVAC of unstable obstetric patients is dangerous. Operational MEDEVACs often challenge aircraft range, occur in poor visibility and require take-off and landing on small, poorly appointed fields and pads. Exposure to extremes of temperature in uninsulated tactical aircraft may exacerbate shock in bleeding patients. Noise, vibration, poor patient access, and poor lighting further complicate patient management in flight. Routine transfer of stable pregnant patients is much safer for all and preserves warfighting assets.
• The operational setting is often environmentally challenging for pregnant women. Extreme heat may exacerbate risk of fainting (and falling). Complicating the management of morning sickness and potential dehydration are the realities of field chow, extreme heat, and porta-potties.

Command Policy usually follows one of three directions:

1. Immediate transfer out of the operational setting.
2. In general, keeping the pregnant woman in the operational setting as long as service guidelines are met.
3. Prompt transfer out of the operational setting when it is tactically convenient.

Each of these approaches has its' merits and it may prove useful for you to discuss with your Command their preference in managing pregnancy.

Cultural considerations: Some religions or cultures attach extreme negative stigma to pregnancy out of wedlock. In some countries, women and their children may be stoned to death for violation of this ethic. When unmarried women are referred to civilian hospitals in some countries for OB care, be very careful. US military providers in some countries routinely transfer their unmarried OB or potential OB patients to more moderate, neighboring countries with a diagnosis that does not denote pregnancy. For example, a woman with cramping and bleeding due to a threatened miscarriage might carry the diagnosis of "abdominal pain." Such a diagnosis is certainly technically correct, although arguably incomplete. Nonetheless, this diagnostic expedient allows for care to be provided discreetly. Unmarried pregnant personnel should be transferred out of all countries with such strong cultural beliefs ASAP to avoid problems. Details on the cultural aspects of care in specific countries can be obtained from a supporting Operations and Medical Intelligence Officer.

Pre-deployment Screening

Starting a reasonable time before deployment, it is important to review the medical records for a variety of gynecologic issues. Perform pre-deployment screening of deploying women for:

1. Up to date Pap smear and pelvic exam with abnormals followed-up.
2. Acute or chronic OB-GYN problems
3. Contraception
4. Pregnancy

Pre-deployment Briefing

Provide a pre-deployment briefing to all deploying women, considering issues related to women's health. Specific areas to brief include:

• Urination issues
• Menstruation issues
• Bathing
• Quarters
• Selection of clothing
• Liberty risks for deployed women
• Leadership
• Host Nation issues
• Pregnancy
• STDs and safe sex

Urination Issues

Urinating in a field environment is sometimes an unpleasant, difficult, time-consuming, and dangerous task for women. To obtain privacy may require the woman to separate from the unit, placing herself in some degree of danger. Undressing sufficiently to urinate without soiling her clothing and then redressing usually requires many minutes. Balancing while squatting to urinate is usually not a practiced skill, and usually requires her to lay down her weapon. Using a fallen log or rock for support is sometimes worse than squatting. Even when sitting-position field latrines are available, they often are no bargain as far as cleanliness, odor, or comfort are concerned. The point is: urinating in the field environment is a function most women seek to avoid or minimize to the greatest extent that is physiologically possible

.For women in military aircraft (helos and C-130's), the situation is not appreciably better. The design of jump and flight suits makes it impossible for a woman to urinate without completely disrobing, an awkward, embarrassing, and time-consuming evolution in the tight quarters of these aircraft.

The primary means by which women avoid this is to not drink any liquids. This can be very effective in limiting urination as it rather quickly leads to dehydration. There are three problems:

• Physical and mental health in the field depend on remaining well-hydrated.
• Physical performance suffers in the presence of dehydration.
• Urinary tract infections are much more common among poorly-hydrated women.

Some women in field operations find it more convenient and private to remain in their tent to urinate. Some have used empty, standard coffee cans with plastic lids (obtained from mess supply). The tent provides privacy and security and the women can urinate into the coffee can, close the lid, and carry it to a latrine for disposal of the urine and rinsing so the can may be re-used at a later time. Other women have used 1-gallon Ziplock bags for the same purpose. They pre-pack their dry clothing and underwear in Ziplock bags for the deployment. As they use up their dry clothing, they have Ziplock bags left over. Inside their tent, they can urinate into an empty bag, zip it closed, and then carry it to the latrine for disposal.

Two products that have been successfully field-tested by military women are the "Lady J" and "Freshette." Both of these enable women to urinate while standing and without extensive disrobing. Each has beneficial features. After opening the BDU fly, the plastic funnel is slipped inside the pants and underwear and held tightly against the vulva. Released urine is caught by the funnel and drains out the spout. The few drops of urine remaining in the system are shaken loose. They may be rinsed and stored for future use.

The Lady J, having a relatively short drain, may not clear the BDU clothing. This requires vigilance to avoid wetting the clothing. The Freshette has a longer spout, clears the BDU clothing, and can be aimed in nearly any direction. With both of these products, some practice is usually required to become proficient.

It is important to stress to deploying men and women the need to stay well-hydrated and drink plenty of fluids. On a Command level, it is important to provide as much opportunity as the tactical situation allows for women to urinate privately, without harassment, in an area close enough to the unit to provide security.

Menstruation Issues

Consider the following information in the pre-deployment brief:

Encourage BCP users to continue their use during deployment. BCP's minimize dysmenorrhea, produce lighter flows (which is much easier to cope with), and eradicates worry of unplanned pregnancy in case of planned or unplanned sex (including rape).

Encourage women with dysmenorrhea, dysfunctional uterine bleeding, problems with Depo-Provera, chronic pelvic pain, and clear need for contraception (history of unplanned pregnancy, recent abortion or delivery, STD's, unprotected intercourse) to start BCP's prior to deployment and stay on them throughout.

Discourage the use of DEPO-PROVERA on deployment unless the patient has been a long term user. DEPO-PROVERA causes a significant number of women to have dysfunctional bleeding which can be troublesome during a deployment. For short deployments, time DEPO-PROVERA shots for delivery in garrison. If you want it in the field, you will need to supplement your AMALs.

Consider the option of prolonged or continuous BCP use without withdrawal. Operationally deployed women can safely use BCPs continuously for many cycles (without the break to allow for a menstrual flow).

Insure women deploy with adequate feminine hygiene products for prolonged periods without resupply. Remind tampon users to change their tampons at least every 8 hours to avoid the risk of infectious complications (PID, toxic shock, etc.)

Use non-deodorant tampons, pads, and panty liners since the perfume can cause a dermatitis or vaginitis, predisposing the individual to further problems.

Whether to bring tampons or sanitary pads on deployment is a personal preference decision, but the following should be considered:

• When operating in the field, wearing full BDUs (Battle Dress, Utility), ECWCS (Extreme Cold Weather Clothing System), boots, flack jacket and tactical equipment, it is time-consuming, difficult, and exposing to undress sufficiently to remove and replace a tampon. It is easier and faster to pull out a pad and replace it.
• Pads provide some protection of the genital area against the muck and grime of some field environments. They also absorb physiologic discharge and any urine leaks. Tampons provide no such protection and may "wick" dirty water up through the string, inoculating the vagina with whatever micro-organisms are present in the water.
• A box of tampons is very small, and takes up very little space in your gear. This is most useful for for extended deployments, but may be important for short deployments as well. A box of pads takes up much more room.
• Minipads or panty liners are a good solution for many field issues. Some women deploy with enough pantyliners to use a fresh one each day. These women plan to wear the pantyliners continuously, to provide protection of their clothing against physiologic discharge and urine leaks. They also provide some protection against vaginal contamination with field water. They reduce the need for field laundering of clothing. Other women use pantyliners only as needed, finding them hot and somewhat uncomfortable, particularly when exercising.

Wet wipes ("Baby Wipes," "Wet Naps," etc.) are very useful during a deployment. They are used not only for genital cleansing (toilet paper is sometimes unavailable or its' quality suboptimal) but also for hand and face washing or "wash cloth baths." Experienced women usually plan on using about 5-6 per day during a field deployment when access to washing and bathing facilities are limited or non-existent. These are taken either in a "travel pack" or, more often, placed in a zip-lock bag.

Bathing

In some operational settings, bathing facilities are plentiful and not an issue. In many other settings, showers may not be available for several days or even a week. Even then, the shower facilities may be suboptimal (field showers are not the same as showers in the barracks), lacking access, and privacy.

Regular bathing is important, both for physical hygiene (preventing skin disease) and mental hygiene.

Bring your own soap to the field and a small bottle of your personal preference for shampoo as you can't count on either one being provided in the field. When privacy is an issue in the shower, wear a nylon, one-piece bathing suit. You can still get very clean, the bathing suit (Speedo type) weighs nearly nothing, and takes up virtually no space in your pack.

Use a low perfume soap (Dove(TM) or Zest(TM) are among the lowest.) or hypoallergenic bar. Prolonged contact with the perfume can predispose the individual to contact dermatitis and a chemical vaginitis.

Quarters

One issue that sometimes proves troublesome in the the quartering or housing of men and women together in field environments. Two general approaches are taken:

1. House the men and women from the same unit together in the same spaces. This will promote unit cohesion and provide uniform protection of all personnel. While this can create some privacy issues for both the men and women, experience has shown that these issues can be largely overcome by artful draping of poncho liners or shelter halves, combined with a generally understood sensitivity to the issue.
2. House the men and women separately. This largely solves the privacy issue, but can create issues of jealousy (your tent is nicer than my tent) and sometimes safety, particularly if the women are housed at some distance from the men. It also interferes with the normal bonding that occurs among members of the same unit. Because of the relatively few women officers and senior enlisted, an additional problem of housing the women separately is limited direct supervision and guidance for the women.

The Commanding Officer will decide which approach is best for this particular operational deployment.

Clothing

It is very useful for a deploying female servicewoman to bring a modest, dark colored, 1 piece, nylon, swimsuit which can be worn for "bathing" if privacy is a problem. Women should leave fragile undergarments at home and opt for sturdier selections. More delicate clothing may be lost from the laundry or clothes line if it survives field laundry.

Sports bras and panties with a high cotton content launder well, support well, and minimize infections (intertrigo and vaginitis).

Wear BDU pants loose. They are normally tailored with a high crotch, which may lead to vulvar irritation and vaginitis unless worn loose in field settings.

What type of underwear to bring is a matter of personal preference, but these issues should be considered:

• Cotton underwear absorbs moisture and "breathes," allowing for circulation of air and promoting dryness in the vulvar area. This, in turn, reduces the chance of developing heat and moisture problems such as intertrigo and monilial infections. However, when engaged in strenuous physical activity (and sweating) over a long period of time, the cotton tends to bunch up into a wet, abrasive mass, leading to chafing and skin abrasions so severe as to be temporarily disabling. It may be unwise to use cotton underwear in field environments in which heavy exercise or  marching long distances is anticipated.
• Nylon or polypropylene underwear or Lycra work-out shorts do not absorb moisture, but rather conduct it. During heavy exercise in field operations, moisture is conducted through the nylon and ultimately is absorbed and evaporated by the cotton in the fatigues (BDUs). The underwear itself remains relatively dry. This property make these types of underwear preferred by many women for exercise-intensive field operations. For sitting around a bivouac area, however, nylon underwear is hot, tends to trap moisture and keep it on the vulva, and may prove uncomfortable.
• Men often deploy on field operations without using any underwear at all. Most women will not find this approach practical, due to the normal physiologic vaginal discharge, the normal occasional leakage of urine and spotting in some women during strenuous physical exercise, and the difficulty in laundering in a field environment. It is much easier to wash out a pair of panties and let them dry overnight than to try to wash BDU (Battle Dress, Utility) pants, which usually won't dry overnight.

Liberty Risks for Deployed Women

The buddy system works best for members of the same sex on liberty. Specific problems encountered by women:

• In most cases the number of operationally deployed women is extremely small. It may be difficult for a woman to find another woman she knows who is off duty at the same time with whom to go on liberty.
• Mixing male and female "buddies" creates problems for both sexes. Men interested in "adult male entertainment" avoid having female buddies. Men and women sharing liberty can establish (or be accused of establishing) inappropriate relationships which can impact marriage and professional performance.
• Some Commanding Officers establish a policy that all women going on liberty must be accompanied by men from the unit. This is obviously a judgment call by the CO, weighing the problems of mixed-gender buddies (above) against the protective effect afforded the women by the presence of the men. Most COs will appreciate your input into that judgment.

The potential for rape on deployment is significant. Deploying personnel should know that every allegation of rape will be formally investigated, even if the alleged victim later recants. If a woman was raped, a serious crime has occurred. If a woman alleges rape when none occurred, that is also a serious crime. No one in the chain of command should ever discount or ignore a report of rape.

Inform deploying personnel that all potential victims will be offered injury and STD evaluation, emotional support, and emergency contraception whether or not they submit to forensic rape examination and/or press charges.

Men deploying with women need to be careful to avoid situations leading to "date rape" allegations (alcohol abuse and sharing hotel rooms for any reason.)

Leadership

In comparison to men, women in the military have relatively fewer leaders in garrison, and this gap widens dramatically during deployment. In the Marine Corps, most units deploy a very small number of very junior women. It is uncommon to find a female SNCO and rarity to find a female officer. Many women find they have no direct supervision or guidance from anyone senior, male or female. It is important to recognize this leadership void and correct it.

Male SNCO's need to go out of their way to take care of subordinate women marines. Female SNCO's and officers need to serve as supervisors, mentors, and spokeswomen for women who do not normally fall within their chain of command.

Women should be encouraged to work together for their mutual safety and comfort. Supervisors should try to schedule female colleagues to work together to facilitate "buddying-up" on liberty as well. Such scheduling also prevents a woman from being alone on duty in isolated areas or traveling to and from places of duty alone at night.

Host Nation Issues

Brief all personnel on the position and conduct of women in the host nation society and encourage American women to conform to local standards of modest female behavior.

• Remember that some foreigners equate American women to Sharon Stone, Demi Moore and other actresses they see in the movies. American women are sometimes perceived as extremely sexually liberated by others.
• In some parts of the world, American servicewomen may attract unwanted attention just by being in the US military. Wear of typical American casual clothes like short-shorts, bikini's and halter tops may be seen as provocative (i.e., "asking for it") in conservative societies.
• Although it's nice to make new friends, American women should avoid situations where they might end up alone with host nation men, especially, in male-dominated societies.

Pregnancy

Place women on light duty and restrict deployment as soon as the HCG is positive. The formal command notification will be made following the new OB appointment. The patient also provides her own official command notification as directed by MCO 5000.13 (Marine Corps), OPNAVINST 6000.1A (Navy), AFI 44-102 (Air Force), or AR 40-501 (Army). Usually, this includes and acknowledgment of her responsibility to provide a written plan to the command that describes how her dependent will be cared for in her absence for duty purposes.

If the pregnancy was unplanned, ask if the patient is considering abortion or adoption. Despite you moral convictions, it is appropriate to refer the patient to a counselor if she would like to discuss options. Elective abortion is not widely available in military hospitals. Many patients seek an abortion at their own expense. Obtain information from your local MTF. It is at the discretion of the Command to allow a woman who is deployed to leave her place of duty to seek an abortion. This is not a MEDEVAC event although space-A travel is possible. Abortion laws and availability in the civilian sector vary throughout the world.

Even in garrison there may be occupational risks to a woman or fetus in an "industrial" work place. Work with Occupational Health to identify risks that can be avoided. Restricting her from all duties is rarely necessary, will short-change the command and may sabotage the patient's career.

Be specific in limitations. For example: "No work with toxic chemicals, no work around fumes in spaces with poor ventilation, no work at heights above 3 feet without adequate protection from falls, etc."

Specific reproductive hazards include:

NOISE

Pregnant women must wear hearing protection when exposed to ambient noise levels above 84dBA, including infrequent impact noise.

Brief exposure (5 minutes per hour or less) of hearing-protected pregnant women to ambient noise above 84dBA in order to transit high noise areas is probably safe. Prolonged exposure to this level of noise is not recommended.

Pregnant women should avoid any exposure to ambient noise greater than 104dBA (corresponding to the need for double hearing protection), unless absolutely essential for quickly moving through a high noise area. The abdominal wall muffles (attenuates) the noise only somewhat and these very noisy areas may pose significant problems for the developing fetus.

HEAT

Most pregnant women tolerate exposure to extreme heat poorly, for several reasons. Among them are the thermogenic effects of progesterone, changes in surface area to mass ratios, and the cardiovascular changes accompanying the pregnancy.

Elevations of maternal core temperatures above 102 degrees are associated with increased risk of fetal malformations and pregnancy loss.

It is wise to restrict prolonged exposure of pregnant women to very high temperatures, such as might be found in a ship's laundry, scullery or engine spaces.

ORGANIC SOLVENTS

These should be avoided while pregnant. Fumes can be a problem, but probably more important are spills that contact the skin.

LEAD, CADMIUM, MERCURY

These can be highly toxic to the fetus.

LOW FREQUENCY WHOLE BODY VIBRATION

Strong, repeated body shaking such as would occur while operating a jack hammer, are ill-advised at any time during pregnancy, but is probably particularly important after the 20th week of pregnancy.

PROLONGED STANDING WHILE ON DUTY

This is associated with more frequent pregnancy problems and should be avoided.

Sexually Transmitted Disease and Safe Sex

It is unlikely than any amount of advocacy will change the morality and sexual attitudes of an adult. Character is well-established long before a person enters the military and it is probably impossible to effectively dictate morality. However, as medical providers, we may need to tell military personnel the medical risks of unprotected sex. Discussions could focus on:

• Risk of death from HIV, Hepatitis B, syphilis and cervical cancer
• Risk of cervical cancer from HPV
• Risk of infertility, sometimes occult, which may follow gonorrhea or chlamydia infections.
• Condoms are reasonably good protection against pregnancy, GC, chlamydia, HIV, Hep B and syphilis. They are not particularly good protection against herpes or HPV.
• Any sexual activity that avoids contact with a partner's body fluids is safer than one that doesn't.
• Sexual abstinence during deployment is the most effective method of preventing STDs and pregnancy.

Aerospace Medicine Issues

The aerospace environment places unique physiologic, mechanical, and logistic stresses on the aviator, male or female. In several important areas, women react differently to these stresses than men, among them:

• G tolerance
• Altitude sickness
• Anthropometrics/strength differences
• Pregnancy concerns

For many reasons, much of the scientific evidence in these areas is only partially developed. Future studies with larger numbers of participants well clarify many of these issues.

Gravitational Forces

In high performance aircraft, aviators and crewmembers can be subjected to 9 Gs (Hypergravity) on a regular basis. This means functioning while forces make them feel up to nine times heavier than normal.

Without countermeasures, people can have physiologic symptoms (loss of vision and G induced loss of consciousness or G-LOC being the most critical) at as low as three Gs. Effective countermeasures include Anti-G Straining Maneuvers (tensing arm and leg muscles with a valsalva) and life support equipment. Improving muscle mass and strength with weight lifting will improve the straining maneuver capability, and good cardiac conditioning enhances endurance.

Each individual aviator has a base line G-tolerance affected by internal and external factors. In general, women have a higher baseline tolerance than men; however, there appears to be variability over menstrual cycles. In one very small study, there appeared to  be a slight decrease in G-tolerance during ovulation and menses, and with certain oral contraceptives.

Dehydration causes loss of G-tolerance in men and women. However, women aviators are more likely to begin a flight in a dehydrated state due to the lack of urinary relief devices in high performance airframes. It is important to encourage adequate hydration and   good availability of lavatory facilities close to the flight line.

Hypoxia and Decompression Sickness

Hypoxia and decompression sickness may have a higher attack rate in women.

Hypoxia is caused by a lack of oxygen to the tissues. Hypoxic hypoxia is caused by a decrease in the available atmospheric oxygen at increased altitudes. If someone is anemic, a more common condition among women, symptoms will occur faster, i.e. at a lower altitude.

Decompression sickness may occur whenever an individual is rapidly exposed to an environment with less than half the initial atmosphere. For instance, if one starts flying at sea level, half of the atmosphere is lost at 18,000 feet. The most common form of decompression sickness in aviation is the "bends", caused by bubbles of nitrogen, usually localizing around joints and manifested by pain.

People with more "fat" are at greater risk for developing the bends. Women, because of their higher body fat composition, are more likely to have intravascular nitrogen bubbles, as a group, than men.  NASA reports while women are more likely to have nitrogen bubbles, they are less likely to report symptoms than men. Studies from Brooks AFB revealed different findings, with women reporting more symptoms than men. Motivation to continue flying may have played a part in these differences.

Anthropometrics

Anthropometrics (size and shape of personnel) affects not only equipment fit, but also cockpit "fit". Smaller stature aircrewmembers of both genders may have difficulty reaching certain controls while maintaining visual reference points in some aircraft.

Life support equipment was designed to fit the 5th to the 95th percentile male in 1950. About half of women will require at some modification of their equipment to obtain a good fit.

Pregnancy in Aviation

In the Air Force, pregnant aircrew members are grounded from all fixed wing airframes during the first and third trimesters, and from ejection seat aircraft for the entire pregnancy. The first trimester grounding is due to increased susceptibility to airsickness and teratogenicity. The third trimester is due to ability to egress and reach controls.

Hypergravity during the first three cellular divisions can lead to fetal loss or birth defects in laboratory animals (birds and amphibians). It is difficult know how to extrapolate these potential risks in humans. Aircrewmember who fly in airframes capable of pulling in excess of three Gs and who experience infertility or pregnancy losses may benefit from temporary grounding until the pregnancy issues are resolved.

Helicopters are noisy and provide sustained low frequency, whole boy vibration. Fetal   noise exposure (threatening to fetal hearing) is only modestly dampened inside the mother's abdomen. LFWBV is associated with placental abruptions. Largely for these reasons, the US Army and USAF bar pregnant women from helicopters for the duration of their pregnancy.

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