Case Discussion by Matt Ciejka, MD
23 year-old female presents with complaint of intermittent left lower abdominal pain for the past 3 days. She also complains of occasional vaginal spotting that began 1 day prior. Her last menstrual period was 26 days ago. She denies any vaginal discharge otherwise. Her abdominal discomfort is characterized as a sharp sensation over the left lower abdomen, lasting for several minutes at a time. She endorses some associated nausea but no vomiting, diarrhea, nor blood in stools. She has not taken anything at home for her symptoms. She denies any lightheadedness or syncope. She has no other complaints at this time.
PMH: HTN, migraines, Graves’ disease
PSH: foot surgery
Meds: propranolol, PTU
Allergies: amoxicillin, Keflex, doxycycline, clindamycin, (all cause hives)
Social history: denies tobacco, alcohol, and illicit drugs
Family history: CHF, diabetes, HTN
Vitals: BP 142/79, HR 106, RR 18, T 36.6, SpO2 99% on RA
Gen: A/Ox3, NAD
HEENT: PERRL, TMs WNL, no rhinorrhea, no oropharyngeal erythema
CV: regular rhythm, tachycardic, no m/r/g
Resp: lungs CTAB, no respiratory distress
Abd: obese, soft, mild tenderness over left lower abdomen, no distension, no peritoneal signs
Musc: 5/5 strength in all extremities throughout
Skin: no rashes appreciated
Neuro: follows all commands, answers all questions appropriately, sensation intact throughout extremities
Pelvic: no vaginal discharge, scant blood in vaginal vault but no active bleeding, no cervical motion tenderness, no palpable adnexal masses, mild tenderness over left adnexal area, slightly enlarged soft uterus
1) Which of the following is the most appropriate next test?
A. Abdominal x-ray
B. Abdominal/pelvic CT scan
C. Abdominal ultrasound
D. Urine human chorionic gonadotropin
E. Progesterone concentration
2) Which of the following is the most common etiology of ectopic pregnancy?
A. Previous medically-induced abortion
B. Previous tubal surgery
C. Intrauterine device (IUD) contraception use
D. History of pelvic inflammatory disease
E. In utero exposure to diethylstilbestrol (DES)
3) Which of the following combinations of ultrasound findings and blood work is most suggestive of an ectopic pregnancy?
A. Fluid in pouch of Douglas on ultrasound; serum progesterone 30 ng/mL
B. Absence of intrauterine gestational sac on transvaginal ultrasound; serum hCG 1,600 miU/mL
C. Absence of intrauterine gestational sac on transvaginal ultrasound; serum hCG 800 miU/mL
D. Absence of intrauterine gestational sac on transabdominal ultrasound; serum hCG 4,000 miU/mL
E. Absence of intrauterine gestational sac on transabdominal ultrasound; serum hCG 2,000 miU/mL
1. (D) Female patients who are of reproductive age and present with complaints of abdominal pain and vaginal bleeding should initially receive a urine or serum pregnancy test. A qualitative urine hCG test is sensitive for detecting early pregnancy with thresholds as low as 10 mIU/mL to 100 mIU/mL, depending on the test brand. The test is 99% sensitive and 99% specific for pregnancy. If the urine hCG test is positive, one can initially perform transabdominal ultrasound examination to determine the location of the pregnancy and help rule out an ectopic. If an intrauterine pregnancy is not visualized, a transvaginal ultrasound examination can be performed. It should be noted that a serum progesterone level may help to ascertain whether or not a pregnancy is viable (>25 ng/mL suggests viability). If the urine hCG test is negative, one should consider other diagnoses such as PID, urinary tract infection or stone, gynecological issues such as fibroids or ovarian cysts, or GI issues such as diverticulitis or appendicitis. For evaluation of these issues, the other listed tests may be beneficial.
2. (D) The risk for ectopic increases secondary to mechanisms that affect the movement of a fertilized egg through the fallopian tube. Such mechanisms can be anatomical, such as tissue scarring, or functional, such as a decrease in fallopian tube motility. Pelvic inflammatory disease is the leading cause of ectopic pregnancy, and at least 50% of first ectopic pregnancies are associated with a history of PID. It is most often caused byN. gonorrheaor C. trachomatis, whose long-term untreated course can damage the structural integrity within fallopian tubes. Other risk factors for ectopic pregnancy include a prior ectopic pregnancy, endometriosis, and tubal and pelvic surgery by way of formed adhesions obstructing the fallopian tubes. Normal fallopian tube motility can also be impeded by hormonal imbalances involving progesterone. A pharmacological elevation of progesterone, such as from progesterone-only OCPs or IUDs is associated with ectopic pregnancy. In utero exposure to diethylstilbestrol (DES) has been shown to increase risk of ectopic pregnancy as well. A history of medically-induced abortion has not been shown to increase risk.
3. (B) The “discriminatory zone” is the range of serum hCG concentrations above which a gestational sac can be visualized consistently. Transabdominal ultrasound examination can consistently detect a gestational sac when the hCG level is greater than 6,500 mIU/mL. Absence of an intrauterine gestational sac on transabdominal ultrasound with hCG level greater than 6,500 is highly suggestive of an ectopic pregnancy. Transvaginal ultrasound is more sensitive for detection of intrauterine pregnancy and has a lower “discriminatory zone” than transabdominal ultrasound, as it can consistently detect intrauterine pregnancy in conjunction with a hCG level greater than 1,500 mIU/mL. Transvaginal ultrasonography with serum hCG level greater than 1,500 mIU/mL is 67-100% sensitive and 100% specific for detecting ectopic pregnancy. However, it must be noted that there is no hCG level at which the possibility of visible ectopic pregnancy can be ruled out with absolute certainty. Serum progesterone levels can identify patients at risk for ectopic pregnancy, although they are not diagnostic of ectopic pregnancy. Serum progesterone concentrations are higher in viable IUPs than in ectopic pregnancies or IUPs that are destined to abort. A progesterone level of 5 ng/mL or less indicates a nonviable pregnancy, such as ectopic or miscarriage, and excludes normal pregnancy with 100% sensitivity. Due to the poor reliability of progesterone levels in detecting ectopic pregnancy, however, serum hCG levels are used more often in conjunction with ultrasound.
Herbst AL, et al. Ectopic pregnancy. Comprehensive gynecology. 2nd ed. St. Louis: Mosby-Year Book; 1992:457–88
Malhotra N, et al. Operative Obstetrics and Gynecology. JP Medical Ltd 2014: 439-440