An image-rich presentation about Abnormal first-trimester scan. It describes how to reach diagnosis using ultrasound during the first trimester

1. ABNORMAL FIRST TRIMESTER
SCAN
DR MAHMOUD ABDEL-ALEEM
PROFESSOR OF OBSTETRICS AND GYNECOLOGY, ASSIUT UNIVERSITY.

2. OBJECTIVES
• What does abnormal first trimester scan mean? : Predictors
of abnormal early pregnancy
• Sonographic signs of abnormal first trimester scan:
• Miscarriage.
• Ectopic pregnancy.
• Molar pregnancy.
• Some abnormal gynecologic lesions during pregnancy.
• Practical management of abnormal sonographic findings during first trimester.

3. • First trimester is defined as the first 13 weeks of
pregnancy following the last normal menstrual period.
It can be divided into a number of phases, each of
which has typical clinical issues. These phases are:
• Conceptus phase: 3-5 weeks
• Embryonic phase: 6-10 weeks
• Fetal phase: 10-12 weeks
• By ultrasound, the pregnancy progresses from a tiny
gestational sac with no visible embryo, to an ~80 mm
fetus with identifiable features and internal organs.

4. WHAT IS NORMAL 1ST ∆ SCAN
• Intra-uterine pregnancy.
• Single
• Living
• In-dates.
• Normal yolk sac
• NT within normal limits.
• No hematoma.
• Free adnexa (apart from normal CL).

6. CLINICALLY ABNORMAL FIRST ∆
•Bleeding:
• Originating from uterus, tubes, amniotic sac with its contents or placenta:
• Ectopic pregnancy
• Miscarriage/ Miscarriage with infection
• Molar pregnancy
• Subchorionic hemorrhage
• Idiopathic bleeding in a viable pregnancy
• Originating from cervix or vagina:
• Infection (Chlamydia, etc.)
• Trauma (e.g. after intercourse, medical treatment)
• Malignancies, especially cervix cancer
• Cervical abnormalities (e.g. excessive friability or polyps)
• Originating from anus, bladder or vulva:
• Hemorrhoids.
• Lacerations of skin due to trauma, malignancy (rare) or infection
• UTI, schistosomiasis

7. •Pain:
• Pregnancy specific.
• Pregnancy non-specific.
• Hyperemesis gravidarum:
•Associated masses:
• Genital.
• Extra-genital.

8. I- THREATENED MISCARRIAGE
• Live intrauterine gestation
• Cervix is closed.
• ± subchorionic haemorrhage.

9. GOOD PROGNOSIS
• FHR> 90 bpm
• Yolk sac < 7 mm
• Small or irregular gestational
sac: MSD/CRL >5 mm
• Small subchorionic haemorrhage <
1/5 of gestational sac
• Small mean gestational sac diameter
• Normal amnion size.
• Normal decidual reaction.
BAD PROGNOSIS
• Fetal bradycardia: <80-90 bpm
• Large and calcified yolk sac of > 7
mm
• Small or irregular gestational
sac: MSD/CRL <5 mm
• Large subchorionic haemorrhage>
2/3 of gestational sac
• Small mean gestational sac diameter
• Expanded amnion sign (an
abnormally large amniotic cavity)
• Absent or poor decidual reaction

10. SUBCHORIONIC HEMATOMA
• Crescentic collection with elevation of the chorionic membrane
• Echotexture is variable:
• Acute: hyperechoic and may be difficult to differentiate from the adjacent chorion
• Subacute-chronic: decreasing echogenicity with time
• There is an extension of the haematoma towards the margin of
the placenta.
• Quantification
• Small: In early pregnancy, if <20% of the size of the sac.
• Large: if >50-66%.

12. II- ECTOPIC PREGNANCY
• The ultrasound exam should be performed:
• TAS: provides a wider overview of the abdomen
• TVS: is important for diagnostic sensitivity.
• Positive sonographic findings include:
• Uterus.
• Empty uterine cavity or no evidence of intrauterine pregnancy
pseudogestational sac or decidual cyst: may be seen in 10-
20% of ectopic pregnancies
• Thick echogenic endometrium.

13. • Tube and ovary
• Simple adnexal cyst: 10% chance of an ectopic
• Complex extra-adnexal cyst/mass: 95% chance of a tubal
ectopic (if no IUP)
• an intra-adnexal cyst/mass is more likely to be a corpus luteum
• Tubal ring sign
• 95% chance of a tubal ectopic if seen
• described in 49% of ectopic and in 68% of unruptured ectopic
• Ring of fire sign: can be seen on colour Doppler in a tubal
ectopic, but can also be seen in a corpus luteum. Absence of
colour Doppler flow does not exclude an ectopic.
• Live extrauterine pregnancy (i.e. extra-uterine fetal cardiac
activity): 100% specific, but only seen in a minority of cases.

14. •Peritoneal cavity
• Free pelvic fluid or hemoperitoneum in the pouch of
Douglas
• The presence of free intraperitoneal fluid in the context
of a positive beta HCG and empty uterus is
• ~70% specific for an ectopic pregnancy.
• ~63% sensitive for ectopic pregnancy

21. III- HETEROTOPIC PREGNANCY
• IVF patients: there is a possibility of a coexisting ectopic
pregnancy in ~1:500.
• Non- IVF patients, the risk of heterotopic pregnancy is
minuscule (1:30,000).

22. IV- PREGNANCY OF UNKNOWN LOCATION
•”PUL” is assigned when neither an (IUP) or an (EP) is
identified on TVS + [+ve] pregnancy test.
•Clinical presentation
• Pelvic pain, vaginal bleeding
• Positive pregnancy test
•A pregnancy of unknown location maybe either:
• Very early pregnancy, not yet detected with ultrasound
• Complete miscarriage
• Unidentified ectopic pregnancy

23. • Sonographic features
• Essentially these patients will present with a "normal" pelvic
ultrasound, with no signs of an IUP and normal adnexa.
• Markers
• Serial ß -hCG: has an adjunct role in the diagnosis of ectopic pregnancy, and is
useful in the follow-up of clinically stable patients. Single reading > 1500-
2000 mIU/mL should be conclusive
• Serum progesterone <5 ng/mL is a good indication of nonviability.
• Larger values cannot exclude an ectopic pregnancy.
• Treatment and prognosis
• In hemodynamically stable patients, serial quantitative beta-hCG
levels and a repeat ultrasound examination in a short interval are
the management of choice.

24. • TVS:
• Empty uterus:
• BhCG:
• > 1500: action: you should diagnose or wait a maximum of 48 hours
and rescan
• < 1500: action: serial BhCG
• Normal rising: san - healthy IUP
• Abnormal rising: scan  PUL or EP or unhealthy IUP.

25. V. FAILED EARLY PREGNANCY
• Death of the embryo and therefore, miscarriage.
• Diagnostic Ultrasound Findings of pregnancy failure: action:
terminate
• Single scan:
• CRL of ≥7 mm and no heartbeat on a transvaginal scan
• MSD of ≥25 mm and no embryo on a transvaginal scan
• Serial scan: (0 >> 4 >> 11)
• Absence of embryo with heartbeat ≥15 days after a scan that showed a
gestational sac without a yolk sac
• Absence of embryo with heartbeat ≥11 days after a scan that showed a

26. •Findings suspicious but not diagnostic
of pregnancy failure: action: wait 7-14
days.
• Single scan:
• CRL: of <7 mm and no heartbeat
• Mean sac diameter (MSD) of 16-24 mm and no embryo
• Serial scan:
• No pulsating embryo 7-13 days after a scan that showed a gestational sac without a yolk
sac
• No pulsating embryo 7-10 days after a scan that showed a gestational sac with a yolk sac
• Absence of embryo ≥ 6 weeks after last menstrual period.
• Amnion seen adjacent to yolk sac, with no visible embryo (empty amnion sign)
• Enlarged yolk sac (>7 mm)

27. GESTATIONAL SAC

28. VI. ANEMBRYONIC PREGNANCY
• This is a subtype of failed intrauterine pregnancy.
• TAS and TVS show a uterus with an intrauterine gestational sac.
• Single scan:
• MSD is at least 25 mm on the transvaginal scan with no embryo
or yolk sac.
• The cervix is long and closed. Both ovaries are normal with no
adnexal mass or free fluid.
• Serial scan:
• ≥11 days after scan showing gestational sac with yolk sac, but
no embryo, or

29. •Suggestive features
• Assessment of interval mean sac diameter (MSD) growth
rate: not useful, due to an overlap between viable and
non-viable pregnancies.
• Absent yolk sac when MSD >8 mm on transvaginal
ultrasound (TVS)
• Poor decidual reaction: often <2 mm.
• Irregular gestational sac shape.
• Abnormally low sac position.

30. VII- PREGNANCY OF UNCERTAIN VIABILITY
(PUV)
•An intrauterine pregnancy with no enough
criteria (usually on ultrasound grounds) to
confidently categorize an intrauterine
pregnancy as either viable or a failed
pregnancy.
•Intrauterine GS with an embryo with CRL <7
mm with no fetal cardiac activity.
•Gestational sac with MSD <25 mm containing

32. TVS
Embryo +ve
≥ 7mm
-ve pulsation
????
< 7mm
-ve pulsations
Rescan 7 days
No embryo
MSD <12 mm
Rescan 14
days
MSD 12-25
mm
Rescan 7 days

33. VIII. INEVITABLE MISCARRIAGE
•Clinically easy to diagnose
• Cervix opened
• Massive bleeding.
•Sonographic signs:
• No cardiac pulsations.
• Opened cervix.
• Displaced intrauterine contents to lower uterine
segment.

35. IX. MOLAR PREGNANCY
• Enlarged uterus
• An intrauterine mass with cystic spaces without any
associated fetal parts
• the multiple cystic structures classically give a "snow storm" or
"bunch of grapes" type appearance.
• Bilateral theca lutein cysts may also be seen on ultrasound
• Color Doppler interrogation may show high velocity with a
low impedance flow

37. IX_1. PARTIAL HYDATIDIFORM MOLE
• Definitive diagnosis by ultrasound is often difficult.
• Described sonographic features include
• Greatly enlarged placenta relative to the size of the uterine
cavity.
• Cystic spaces within the placenta ("molar placenta"), which may
not always be present
• An amniotic cavity (gestational sac), either empty or
containing amorphous small fetal echoes which may be
surrounded by a relatively thick rim of placental echoes

38. • Presence of a well-formed but growth-retarded fetus,
either dead or alive with hydropic degeneration of
fetal parts being frequently present
• Colour Doppler interrogation may show high velocity
and low impedance flow

40. X- DEMISE OF A TWIN
•A complication that can occur in a twin pregnancy.
May be due to many factors.
•May lead to either:
• Vanishing twin syndrome: only one fetus may be identified
on ultrasound of a previously documented twin
pregnancy, and this may be due to resorption or
miscarriage of the demised twin.
• Fetus papyraceus: Once the twin dies, most of the dead
twin tends to be absorbed leaving behind a small flattened
remnant.

42. CONCLUSIONS