| Related Article: Maternal Mortality and Immortality - Part 1 |
The number one leading cause for maternal death worldwide is hemorrhage; in the United States it is number two. The typical pregnancy lasts 40 weeks and the causes for maternal bleeding can be divided into three stages: the first 20 weeks, the second 20 weeks, and labor and delivery. However, keep in mind that trauma can cause vaginal bleeding during any phase of pregnancy. Here is a look at the first and second 20 weeks.
Gestation
In the fertile female, each month is an opportunity for reproduction. The lining of the uterus (endometrium) increases its blood supply and thickens in preparation to receive a fertilized human egg. One of the ovaries produces this egg (ovum) each month in preparation for fertilization. If fertilization fails to occur, the thickened endometrial lining is no longer needed and begins to detach from the uterine wall, thus producing the monthly period or menses. However, there will be an opportunity next month. And at any time during the egg’s monthly journey from ovary to uterus, it may be fertilized by roaming spermatozoa: day one of human construction.
Normally the ovum is fertilized when it travels through the fallopian tube (salpinx). As the fertilized ovum continues to move toward the uterus it develops into a mass of reproducing cells called a zygote. By the time it gets to the uterus, the zygote has transformed into a larger and more organized ball of cells called a blastocyte.
Total transit time from ovary to implantation of the blastocyte in the uterus is about one week. The side of the blastocyte that ends up against the endometrium becomes the placenta, while the outer side begins formation of the embryo. The amniotic sac and fluid then develop to provide a safe growth environment. Once the majority of organs are formed, around 10 weeks, the embryo becomes a fetus. And it stays a fetus until it is unplugged from maternal life support, becoming an infant upon delivery.
Since the size of the pregnancy at any given time can impact maternal hemorrhage, the following list gives you an idea of uterine content based on weeks of gestation (growth).
- 4: tiny
- 8: kidney bean
- 12: 2.0 inches; 0.5 ounce
- 16: 4.5 inches; 3.5 ounces
- 20: 6.5 inches; 10.5 ounces
- 24: 12 inches; 1.5 pounds
- 30: 16 inches; 3.0 pounds
- 34: 18 inches; 4.75 pounds
- 38: 20 inches; 7.0 pounds *weight is variable by this stage due to influences from genetics, disease (diabetes), habits (smoking, alcohol, drugs), etc.
The First 20 Weeks
The major sources for maternal bleeding during this time period are ectopic pregnancy and miscarriage.
Ectopic means ‘out of place,’ thus an ectopic pregnancy is one that occurs outside of the uterus, most often in the fallopian tube. Less than 5 percent occur at other sites such as in the abdomen or at the narrow corner of the uterus where the tubes enter (cornua). Risk factors for an ectopic pregnancy include those things that will narrow the salpinx, thus making it difficult for the egg to pass: infection of the tube (salpingitis), prior ectopic pregnancy, and previous tubal or pelvic surgery.
The classic presentation for an ectopic pregnancy is a history of missed menses, abdominal pain/tenderness, and vaginal bleeding. Even though the pregnancy is not inside the uterus, it produces hormones that maintain the thickened endometrial lining. When the pregnancy is no longer functional, the lining will deteriorate and produce vaginal bleeding. Bleeding can also occur internally from a ruptured ectopic pregnancy and is a leading cause of maternal death in the first 12 weeks of pregnancy.
There are two hospital treatment options. Surgery is indicated if the ectopic has ruptured or if it is too large for the administration of methotrexate. Methotrexate is a cancer drug that can be used to stop the growth and facilitate breakdown of an early, small ectopic pregnancy, thus avoiding surgery.
More commonly, vaginal bleeding during the first 20 weeks is due to a miscarriage. A miscarriage is a pregnancy that ends before the fetus could possibly survive outside of the uterus, generally around 24 weeks, although there are reports of survival before then. Some sources define miscarriage as any pregnancy loss before 20 weeks.
The tissue expelled during a miscarriage is termed the “products of conception,” which is the developing cells, embryo or fetus and placenta, depending on how far the pregnancy has progressed at the time of miscarriage. Most often the pregnancy fails due to abnormal development of the embryo or fetus that is incompatible with its survival.
Early miscarriages frequently go unrecognized and may be noticed only as a heavier and/or later than normal period. This is because in the early period of pregnancy, the products of conception are small and therefore more easily expelled during a miscarriage, decreasing the potential for blood loss. However, as the products of conception increase in size, and the uterus (and its blood supply) also enlarge, the potential for excessive bleeding amplifies. Uterine cramping generally accompanies a miscarriage until the products of conception are expelled, thus allowing the uterus to contract down and decrease bleeding.
Hospital treatment may require a dilation and curettage (D&C) to remove any retained tissue. After appropriate anesthesia, small metal probes of increasing diameter are used to dilate the opening to the uterus to allow insertion of instruments to remove the tissue. A specialize suction device can be inserted into the uterus to remove loose tissue. A curette is a device with a sharp-edged loop at one end and a handle at the other. It is used to gently scrape any tissue still stuck to the inside of the uterus. The goal is to remove all pregnancy related tissue to allow the uterus to clamp down and slow the bleeding. If any tissue is passed in the field, make sure to bring that along with the patient. It may be sent to a pathologist to look for abnormalities.
The Next 20 Weeks
Vaginal bleeding after the first 20 weeks but prior to labor and delivery is generally associated with the placenta, either abnormal position or premature separation. Placenta praevia is where the placenta covers all or part of the cervix of the uterus, exposing the very vascular underside of the placenta that normally would be totally stuck to the endometrium. Typically it is not associated with pain. Major risk factors include having a previous delivery, a current pregnancy with twins/triplets/etc., or previous surgery such as cesarean section or other uterine surgery.
A placental abruption is where part of the placenta pulls away from the uterus, which obviously can cause bleeding as well as abdominal pain/tenderness and uterine cramping. If the abruption occurs in the central portion of the placenta, one or two liters of blood may be hidden in that space. Major risk factors include having a previous delivery, age over 35, previous abruption, and hypertension.
Summary
For prehospital care in the first 20 weeks of pregancy, vaginal bleeding with abdominal pain is an ectopic pregnancy until proven otherwise. Miscarriages occur frequently, often unrecognized; however can present with pelvic cramping and brisk bleeding. The next 20 weeks are fairly quiet from a vaginal bleeding perspective unless the patient develops a placenta praevia, experiences a placental abruption or suffers abdominal, pelvic or vaginal trauma. Recognizing the potential for shock from any of these conditions is the key to directing your treatment in the field.
References
- Coppola PT, Coppola M. Vaginal Bleeding in the first 20 Weeks of Pregnancy. Emergency Medicine Clinics of North America 2003;21:667-677.
- Sinha P, Kububa N. Ante-partum hemorrhage: An Update. Journal of Obstetrics and Gynecology 2008;28(4):377-381.
- Mercier FJ, Van de Velde M. Major Obstetric Hemorrhage. Anesthesiology Clinics 2008;26:53-66