Ectopic Pregnancy Case File

Ectopic Pregnancy Case File

Eugene C. Toy, MD, Lawrence M. Ross, MD, PhD, Han Zhang, MD, Cristo Papasakelariou, MD, FACOG

CASE 30

A pregnant 19-year-old female who has borne one healthy child is being seen at 7 weeks’ gestation based on her last menstrual period and her complaints of vaginal spotting and lower abdominal pain. She denies the passage of any tissue through the vagina, trauma, or recent intercourse. Her medical history is significant for a pelvic infection approximately 3 years previously. On examination, her blood pressure is 90/60 mmHg, heart rate is 110 beats/min, and temperature is within normal limits. The abdomen is normal, and bowel sounds are present and normal. On pelvic examination, the external genitalia and uterus palpate as normal. There is moderate right adnexal tenderness with palpation. Quantitative human β-corticotropin gonadotropin is 2300 mIU/mL, and a transvaginal sonogram displays an empty uterus and some free fluid in the cul-de-sac.

⯈ What is the most likely diagnosis?

⯈ What is the cause of the hypotension?

ANSWER TO CASE 30:

Ectopic Pregnancy

Summary: A 19-year-old female who has borne one child is seen at 7 weeks’ gestation by last menstrual period and vaginal spotting. She has a history of a pelvic infection. Her blood pressure is 90/60 mmHg, heart rate is 110 beats/min, and the abdomen is mildly tender. Pelvic examination shows a normal uterus and some moderate adnexal tenderness. Quantitative human β-corticotropin gonadotropin is 2300 mIU/mL, and transvaginal sonogram shows an empty uterus and some free fluid in the cul-de-sac.

• Most likely diagnosis: Ectopic pregnancy

• Cause of the hypotension: Ruptured ectopic pregnancy in the uterine tube with bleeding into the abdominal cavity

CLINICAL CORRELATION

An ectopic pregnancy results when a blastocyst implants outside the lumen of the uterus. The vast majority of ectopic pregnancies occur in the uterine tube (95 to 97 percent), in either the ampulla, the usual site of fertilization; or the isthmus, the narrowest portion. Any condition that might prevent or delay transport of the zygote to the uterus may cause an ectopic tubal pregnancy, and this patient’s history of a pelvic infection (pelvic inflammatory disease) is a risk factor. Tubal ectopic pregnancies will usually rupture during the first 8 weeks of pregnancy, typically resulting in abortion of the embryo and intraabdominal hemorrhage, with resultant hypotension and tachycardia. Tubal pregnancy in the narrow isthmus tends to rupture sooner than those in the ampulla and produce greater hemorrhage than implantation in the ampulla. Blastocysts implanted in the ampulla may be expelled into the abdominal cavity, where they may reimplant on the surface of the ovary, the peritoneum of the rectouterine pouch (of Douglas), mesentery, or organ surface. Severe hemorrhage typically results from an abdominal ectopic pregnancy, and the resulting hypotension may be emergent. The free fluid seen on ultrasound is blood that has resulted from the ruptured ectopic pregnancy.

APPROACH TO:

The Internal Female Genital System II

OBJECTIVES

1. Be able to describe the anatomy of the uterine tubes

2. Be able to draw the blood supply to the ovaries, uterine tubes, and uterus

DEFINITIONS

ECTOPIC PREGNANCY: Pregnancy outside of the normal endometrial implantation site, usually involving the fallopian tubes

HEMOPERITONEUM: Blood collecting inside the peritoneal cavity, usually leading to abdominal pain and irritation to the intestines

HUMAN CHORIONIC GONADOTROPIN: Glycoprotein molecule produced by the trophoblastic cells of the pregnancy

DISCUSSION

The uterine (fallopian) tubes (see Case 29) extend posterolaterally from the uterine horns and are divided, from medial to lateral, into four regions. The uterine or intramural portion lies within the wall of the uterus. The narrowest portion, or isthmus, lies just laterally to the uterine horns. More laterally, the widest and longest portion of the tube is the ampulla. This is the usual site of fertilization. The most lateral portion or infundibulum is funnel-shaped. The lumen of the infundibulum faces posteriorly into the abdominal cavity, inferior to which is the rectouterine pouch (of Douglas). The margin of the infundibulum is arranged in a series of fingerlike structures called fimbriae, one of which is usually attached to the ovary. This attachment helps keep the infundibulum in close anatomical relation to the ovary, which, in turn, helps ensure that an ovulated egg will enter the lumen of the tube. The uterine tube is supported by the mesosalpinx portion of the broad ligament (Figure 30-1).

Figure 30-1. The female pelvis and internal organs (superior view). (Reproduced, with permission, from Decherney AH, Nathan L. Current Obstetric and Gynecology Diagnosis and Treatment, 9th ed. New York: McGraw-Hill, 2003:33.)

The ovaries, uterine tubes, and fundus of the uterus are supplied by the ovarian arteries, which arise from the abdominal aorta just inferior to the renal arteries (in a manner similar to that described for the testicular arteries). The arteries descend, crossing the ureters anteriorly, and also cross the iliac vessels anteriorly at the pelvic brim. The ureters lie just medial at the pelvic brim. The arteries enter the lateral pole of each ovary, supply it, and continue medially between the layers of the mesosalpinx, close to its attachment to the uterine tube. Each artery supplies the tube, continues on to supply the fundus of the uterus, and anastomoses with the artery from the opposite side. The isthmus and uterine portions of the tube also receive blood from ascending branches of the uterine arteries, which anastomose with the ovarian artery. This accounts for the increased hemorrhage with a ruptured tubal pregnancy of the isthmus. Venous drainage from these structures is primarily through the ovarian veins, which empty into the IVC on the right side and into the left renal vein on the left side.

COMPREHENSION QUESTIONS

30.1 A 22-year-old woman is noted during surgery to have a 3-cm ectopic pregnancy involving the ampulla of the fallopian tube. Which of the following best describes this location of the tube?

A. Portion within the muscle of the uterus

B. Portion that is narrowest and mobile

C. Portion that begins to widen distally and is the longest portion of the tube

D. Portion with fingerlike projections

30.2 Bilateral oophorectomy is performed in a woman who had ovarian cancer. To accomplish this procedure, the ovarian arteries were ligated. Which of the following describes the anatomy of the ovarian vessels?

A. Right ovarian artery arises from the right renal artery.

B. Right ovarian vein drains into the vena cava.

C. Left ovarian artery arises from the left internal iliac artery.

D. Left ovarian vein drains into the vena cava.

30.3 A 3-cm ectopic pregnancy of the isthmus of the left tube is noted to have ruptured, leading to hemorrhage. The blood noted arises principally from which of the following?

A. Uterine artery

B. Ovarian artery

C. Uterine and ovarian arteries

D. Neither the uterine nor the ovarian arteries

ANSWERS

30.1 C. The ampulla of the tube, which is the most common location of ectopic pregnancies, is the part of the tube that begins to widen at the distal end of the tube.

30.2 B. Both ovarian arteries arise from the abdominal aorta. The right ovarian vein drains to the vena cava, whereas the left ovarian vein drains into the left renal vein.

30.3 C. The uterine artery (ascending branch) and the ovarian artery anastomose to provide blood supply within the mesosalpinx to the tube.

ANATOMY PEARL

⯈ The usual site of fertilization is the ampulla of the uterine tube.

⯈ The posteriorly facing ostium of the tube accounts for abdominal ectopic pregnancies usually occurring in the rectouterine pouch.

⯈ The ovarian artery supplies the ovary, uterine tube, and fundus of the uterus. Anastomosis with the uterine artery occurs in the region of the isthmus.

References

Gilroy AM, MacPherson BR, Ross LM. Atlas of Anatomy, 2nd ed. New York, NY: Thieme Medical Publishers; 2012:230, 237, 243, 247. 

Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy, 7th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014:382−385, 392. 

Netter FH. Atlas of Human Anatomy, 6th ed. Philadelphia, PA: Saunders; 2014: plates 340−342, 350−353.

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