Background: Pregnancy of unknown location (PUL) is defined as the situation when the pregnancy test is positive but there are no signs of intrauterine pregnancy or an extrauterine pregnancy via transvaginal ultrasonography (TVUS). PUL is not a final diagnosis and PUL does not mean an ectopic pregnancy. The final diagnosis is arrived at by transvaginal ultrasonography and measurement of serum human chorionic gonadotropin (hCG). It is not always possible to arrive at a final diagnosis, however identifying ectopic pregnancy in these patients at the earliest is very essential as ectopic pregnancy is a potentially lethal obstetric emergency. Women who were admitted with Pregnancy of unknown location PUL and followed up forms the cohort of this study.

Aim of the study was to study the prognosis of patients with pregnancies of unknown location in correlation with Serum Beta hCG levels and the rate of change of β hCG levels.

Methodology: This study was conducted at Sree Avittom Thirunal Hospital, Government Medical College, Trivandrum, a retrospective cohort of patients admitted with pregnancy of unknown location a tertiary care center for period of 1 year.

Statistical tests used are mean, SD, Percentage, chi square and Odds Ratio to assess association of the selected parameters with the Ectopic pregnancy.

Results: Of the 99 patients who met the inclusion criteria  26 were eventually diagnosed ectopic pregnancies, 34 were failing or self resolving pregnancy of unknown location, and 39 were viable intra uterine pregnncy.The majority of patients were in 25 - 29 yrs age group with mean age 26.87yrs. The patients in Intra Uterine pregnancy group where the maximum number of patients were in the group of 20 – 24 yrs.( X² =12.4,P =0.001) The association of gravidity and outcome was found significant with Chi-square =20.58; P =0.008. The majority of patients in Intra Uterine group were primi gravidas. Patients with PUL who had a past history of ectopic pregnancy and prior adominal surgery were seen to be at statistically significant high risk for ectopic pregnancy.

51 out of 60 cases with Beta hCG <1500 or 85% were symptomatic and 15% were asymptomatic. The difference in the mean Beta hCG at the time of presentation was found to be significant statistically. (ANOVA, F=8.331, P=0.000) in that the mean value was significantly lower for failing PUL in comparison to the EP and IUP groups. However, these values are not adjusted to the gestational age at presentation, and hence no reliable conclusions can be drawn. In cases with Beta hCG below the discriminatory zone at the time of presentation, majority (48.33%) were non-viable failing PUL, 31.66% were eventually viable IUPs while 20% were ectopic. There was statistical significance to this finding. (X²=3.263, P=0.001)85.29% of failing PUL presented with low Beta hCG.

Rate of change of Beta hCG from day 0 to day 2 was statistically significant with chi square X²=92.469, P=0.000.Among cases showing more than 66% rise, 87.9% were IUP, 9.1 % were EP and 3.0% were non-viable pregnancies. When rate of change of Beta hCG and Outcome was also studied with a Lower Cut Off of ‘Normal Rise’ in 48hrs. This association was also significant (X²=92.469, P=0.000) A suboptimal rise of less than 50% detects a higher risk of an unfavorable outcome (73.9%) than a suboptimal rise of less than 66% (63%).Similar to the result with rate of change of Beta hCG between day 2 and day 0, the rate of change in serial values on day 4 and day 2 also yields statistically significant results. (X²=35.953, P=0.000).

In fact the course of rate of change of serial serum hCG after the initial 48 hrs actually provides more diagnostic information, in that only 6.7% of cases mimicked the normal “doubling” of viable IUP as compared to the initial 11.5%.

Conclusion: The management of PUL is highly crucial, the definitive diagnosis of a woman with either a failed IUP or ectopic pregnancy has important clinical consequences. The PUL should be assessed by employing experienced doctors and using high quality ultra-sonography in early pregnancy units. Among the several hormones evaluated in the prediction of PUL outcome serum hCG level is the most useful hormone; however, evaluating the changes in hCG serum levels within 48 hours is a more reliable method than a single measurement. It is very important to follow-up the patients diagnosed with PUL until the final diagnosis is concluded.

Keywords- Pregnancy of unknown location (PUL), Beta Human Chorionic Gonadotropin, Ectopic Pregnancy, Failing PUL.