Ectopic Pregnancy: Risk factors, Clinical Features & Differential Diagnoses

Ectopic pregnancy is the development of a fertilized ovum outside of the uterine cavity (e.g., in the fallopian tube, ovary, cervix, or abdominal cavity). The ectopic site can rarely sustain the pregnancy beyond several weeks, at which time the implantation site ruptures.

PATHOGENESIS

The fertilized ovum implants at the ectopic site, stimulating a persistent corpus luteum. The resultant elevated estrogen levels stimulate endometrial growth, and progesterone maintains this lining for uterine implantation that never arrives. The ectopic pregnancy continues to proliferate until it outgrows its blood supply and involutes or ruptures.

RISK FACTORS are generally related to tubal dysfunction or injury and include:

a) Tubal anomalies (e.g., hypoplasia, diverticula)

b) Salpingitis (characterized by inflammation, scarring, and lumen narrowing)

c) Tubal adhesions (e.g., from infection or endometriosis)

c) Previous tubal surgery (e.g., salpingostomy, tubal ligation)

d) Intrauterine device use

e) Previous ectopic pregnancy

CLINICAL FEATURES

The “classic triad” of a missed period, abdominal pain, and a palpable mass on examination are present in fewer than 30% of patients. Important historical and clinical findings include the following:

1. Menstrual history: A history of amenorrhea or a late period is common in patients with ectopic pregnancy. Only 10% of patients describe a normal last menstrual period.

2. Abdominal pain or tenderness: Ninety percent of patients complain of abdominal or pelvic pain.

a) The pain usually begins as colicky and diffuse (as a result of ectopic distention and inflammation) and later becomes localized (as a result of inflammation of the adjacent abdominal wall and local bleeding).

b) Peritoneal symptoms may be noticed if the bleeding causes diffuse peritoneal irritation. With severe bleeding and peritonitis, the abdomen will be rigid, distended, and tender.

3. Cervical motion tenderness [It is cervical excitation that is observed while performing the pelvic examination and is a classical sign suggestive of pelvic pathology] or adnexal tenderness [pain on touch, in the area of a woman's uterus ] is highly suggestive of a pathologic process. Adnexal tenderness is a likely finding in ectopic.

4. Vaginal bleeding: Fifty percent to 90% of patients will note abnormal bleeding, ranging from spotting to heavy flow with large clots.

5. Uterine enlargement: In pregnancy, the uterus softens and grows in response to hormonal stimulation regardless of the site of conceptus implantation. One cannot assume the pregnancy is intrauterine based on uterine size.

6. Palpable mass: Experienced examiners may note a unilateral or cul-de-sac mass, although the absence of such a mass does not rule out an ectopic pregnancy.

7. Volume depletion: Tachycardia, orthostatic hypotension, near-syncope, abdominal pain, and a positive pregnancy test in an otherwise healthy woman are indicative of a ruptured ectopic pregnancy until proven otherwise.

DIFFERENTIAL DIAGNOSES 

— Miscarriage

— Ovarian cyst

— Vaginitis

— Cervicitis

— Salpingitis

— PID

— Combined pregnancy (i.e., intrauterine and ectopic, may be seen in patients taking infertility medications)

— Normal intrauterine pregnancy

— Appendicitis

— Urinary tract infection

— Acute nephrolithiasis

— Enteritis

— Diverticulitis