Dr Catherine Magee Clinical Fellow EARLY PREGNANCY PITFALLS Guys and St. Thomas’ NHS Foundation Trust CONTENTS

Why / who / when should we scan? Role of biochemical markers Scan findings:  Pregnancy of Unknown Location  Ectopic pregnancies  Miscarriage Difficulties in diagnosis SCANNING IN THE EARLY PREGNANCY UNIT

Why  Determine the location and viability of a pregnancy Who  Symptomatic  Reassurance scan  Dating scan  Post miscarriage / termination When  At presentation  Positive urinary pregnancy test  No need for blood HCG / progesterone prior to scan BIOCHEMICAL MARKERS

BHCG  Hormone produced by the placental trophoblast  Detected in plasma or urine 8 days post ovulation  Peaks at 8-10 weeks gestation  Trend gives indication of pregnancy viability  Typically doubles over 48 hours in viable intrauterine pregnancies  Not used to establish gestational age  Not used to diagnose location of pregnancy  Used to plan management of ectopic pregnancy BIOCHEMICAL MARKERS

Progesterone  Hormone produced by ovaries  Causes endometrial lining to thicken after ovulation  Continued production by corpus luteum after fertilisation / implantation  Usually high in viable intrauterine pregnancies, low in failing pregnancies  Not useful in predicting ectopic pregnancies  No need for serial progesterone levels WHEN SHOULD WE SCAN?

Discriminatory zone for intrauterine pregnancies Not the case for ectopic pregnancies Therefore don’t need bloods prior to first scan PREGNANCY OF UNKNOWN LOCATION

Positive pregnancy test but unable to visualise pregnancy on ultrasound Pregnancy site not visualised on between 8-31% of scans Three eventual possibilities:  Viable IUP  Failing pregnancy / miscarriage  Ectopic pregnancy PUL

Symptoms Scan findings  Blood in pelvis  Tenderness on scanning  Endometrial thickness Gestation  Assisted conception  Unknown dates  Irregular cycle PUL

Must have BHCG and progesterone levels Follow up as per results Algorithms ECTOPIC PREGNANCIES

Pregnancy implanted anywhere outside the endometrial cavity Most commonly tubal Incidence 11/1000 pregnancies in UK 2-3% of women presenting to Early Pregnancy Unit Known risk factors DIFFICULTIES WITH ECTOPIC PREGNANCIES

Often present with vague / atypical symptoms Majority will not have known risk factor Can have with low HCG If a patient has ‘passed tissue’ – does not rule out ectopic Endometrium can be of varying thickness Pseudosac can mimic early gestation sac Can have other adnexal masses with different pathology Cervical ectopics can mimic miscarriage ENDOMETRIAL THICKNESS EARLY GESTATIONAL SAC VS PSEUDOSAC

Anechoic sac with trophoblastic reaction Irregular Eccentrically located Centrally located in endometrial cavity Blood flow when Colour Doppler applied Also consider decidual cysts Negative sliding sign Intradecidual sign Double decidual sign WHICH ARE EARLY GESTATIONAL SACS? ADNEXAL MASS CERVICAL ECTOPIC

Cervical pregnancies are rare, accounting for less than 1% of all ectopic gestations. Ultrasound criteria for diagnosis  Empty uterine cavity.  A barrel-shaped cervix.  A gestational sac present below the level of the internal cervical os.  The absence of the ‘sliding sign’.  Blood flow around the gestational sac using colour Doppler CERVICAL ECTOPIC VS. MISCARRIAGE THE CORPUS LUTEUM

Cyst like structure on ovary Different appearances / sizes  Hypoechoic cyst  Solid  Haemorrhagic Classic ‘ring of fire’ when Doppler applied Can be bilateral  Twin / heterotopic pregnancy Note also number of embryos transferred MISCARRIAGE

Delayed / missed  Empty sac with MSD >25.0mm  CRL with no FH >7.0mm

 If CRL <7mm with no FH, must repeat TV US in 7 days

 Always offer 2nd opinion  Should diagnose on transvaginal scan  If TA scan must have repeat in 14 days Incomplete / Retained products of conception Complete

DIAGNOSING MISCARRIAGE

Differences in intra- and inter-observer measurements 2011 study by Pexters et. al  18.8% difference in measurements of gestational sac (inter-observer)  14.6% difference in measurements of CRL (inter-observer)  11.4% difference in measurements of CRL (intra-observer)

Guidelines changed in 2011 to be 100% specific for the diagnosis of miscarriage ie. larger CRL and GS measurements OTHER DIFFICULTIES

Chorionic bumps Fibroids Adenomyosis Uterine anomalies

COMPLETE MISCARRIAGE?

History of heavy PVB with thin endometrium Approx 5% of these will actually have ectopic pregnancy If the first scan, always clarify with biochemical markers and follow up CONCLUSIONS

Ultrasound is gold standard for diagnosis in early pregnancy Early Pregnancy Unit is a multi disciplinary team Be aware of difficulties If in doubt – 2nd opinion or wait and rescan