Ultrasound in obstetrics Ultrasound in obstetrics

By By

Dr. Khattab KAEODr. Khattab KAEO

Assis. Prof. of Obstetrics and Gynaecology Assis. Prof. of Obstetrics and Gynaecology Faculty of Medicine, Al-Azhar University, Faculty of Medicine, Al-Azhar University,

DamiettaDamietta

Introduction Introduction

– Ultrasound has a frequency >20 000 Hz (20kHz). Ultrasound has a frequency >20 000 Hz (20kHz). However, ultrasound machines have frequencies However, ultrasound machines have frequencies of 2-10 mega Hz (MHz). of 2-10 mega Hz (MHz).

– Higher frequencies give better resolution, but Higher frequencies give better resolution, but decreased tissue penetration; thus, used to decreased tissue penetration; thus, used to examine near structures. Conversely, lower examine near structures. Conversely, lower frequency probes are used to examine deep frequency probes are used to examine deep structures. For instance, abdominal probes give 3-structures. For instance, abdominal probes give 3-5 MHz, while vaginal probes give 5-7.5 MHz. 5 MHz, while vaginal probes give 5-7.5 MHz.

– It is best to reduce 'depth' as much as possible. It is best to reduce 'depth' as much as possible. – Increasing the 'gain' increases the echoes, and Increasing the 'gain' increases the echoes, and

thus, may improve the image where obesity is thus, may improve the image where obesity is csausing attenuation. csausing attenuation.

Early pregnancy scanningEarly pregnancy scanning

Aim:Aim: To determine location of To determine location of pregnancy (intra- or extra-uterine), pregnancy (intra- or extra-uterine), viability, gestational age and fetal viability, gestational age and fetal number, in addition to adnexal number, in addition to adnexal pathology (an ovarian cyst mostly). pathology (an ovarian cyst mostly).

Uterine abnormalitiesUterine abnormalities may be seen as an may be seen as an

empty cavity adjoining the pregnancy sac. empty cavity adjoining the pregnancy sac.

Gestational sac:Gestational sac: It could be detected by TAS from 6 It could be detected by TAS from 6

weeks’ amenorrhoea, while TVS may weeks’ amenorrhoea, while TVS may detect it from 4.5 weeks (2-4mm). detect it from 4.5 weeks (2-4mm).

Normal sac growth is 0.7-1 mm/day. Normal sac growth is 0.7-1 mm/day.

It is considered abnormal if its tro-It is considered abnormal if its tro-phoblastic reaction is <2 mm. phoblastic reaction is <2 mm.

Shape of the sac may be affected by Shape of the sac may be affected by uterine contraction or bladder uterine contraction or bladder fullness.fullness.

The embryo:

•Yolk sac (10mm) is the first structure to be seen within the sac. It should be detec-ted within an intrauterine gestational sac of a 20 mm diameter using TAS, or 8 mm using TVS. It is first seen at 5 weeks’ gestation on TVS and at 6 weeks on TAS. It has no predictive value but confirms that the pregnancy is intrauterine. •Embryo is first visible with heart pulsa-tion on TVS at 5 weeks (2-4mm embryonic length). • Heart tone is first visible on TVS at 6.5 weeks (sac diameter of 15-20 mm).

Early pregnancy assessment clinic Early pregnancy assessment clinic

(EPAC)(EPAC) Aim:Aim: avoidance of admission or reduced avoidance of admission or reduced

hospital stay (& cost). hospital stay (& cost).

Ultrasonography results:

# Viable intrauterine pregnancy: Most women are suitable for immediate discharge and GP

follow-up.

# Fetal pole, # Fetal pole, no cardiac activityno cardiac activity: Some : Some are viable, while others represent are viable, while others represent delayed miscarriage. Early embryos delayed miscarriage. Early embryos typically appear adjacent to the yolk typically appear adjacent to the yolk sac in the periphery of the gesta-sac in the periphery of the gesta-tional sac. tional sac.

CRL is the key for management.CRL is the key for management.

CRL CRL 6mm = home & re-scan in 7-10d6mm = home & re-scan in 7-10d

CRL >6 mm = termination. CRL >6 mm = termination.

A dead embryo of CRL >6mm and no cardiac activity as seen by M mode ultrasonography.

# # Empty gestational sac:Empty gestational sac: Some are viable, Some are viable, while others represent blighted ovum. The while others represent blighted ovum. The mean sac diameter (MSD = the mean of 3 mean sac diameter (MSD = the mean of 3 perpendicular measurements), rather than perpendicular measurements), rather than volume, is the key for management. volume, is the key for management.

MSD MSD 20mm = home & re-scan in 7-10 d. 20mm = home & re-scan in 7-10 d.

MSD >20 mm = termination of pregnancy. MSD >20 mm = termination of pregnancy.

You should look for a second opinion. You should look for a second opinion.

Empty gestational sacs (absent embryo, even if amniotic sac is seen [arrow]). Arrow heads point to thin decidual reaction. The lowermost sonogram shows an abnormally large yolk sac, presented for comparison with the first one sonogram.

# # Retained productsRetained products of conception: Mixed of conception: Mixed echogenicity with irregular echo-bright echogenicity with irregular echo-bright areas (it is difficult to differentiate blood areas (it is difficult to differentiate blood clots from retained tissues). Mostly the clots from retained tissues). Mostly the tissue is of <30 mm maximum diameter tissue is of <30 mm maximum diameter with light blood loss and no signs of with light blood loss and no signs of infection, and so, management is infection, and so, management is conservative. Large volume of tissue or conservative. Large volume of tissue or heavy blood loss = evacuation. heavy blood loss = evacuation.

# Empty uterus: Differential diagnosis: 1- very early pregnancy; 2- # Empty uterus: Differential diagnosis: 1- very early pregnancy; 2- complete miscarriage; or 3- ectopic pre gnancy. complete miscarriage; or 3- ectopic pre gnancy.

Consider: 1- history for risk factors for ectopic pregnancy, 2- Consider: 1- history for risk factors for ectopic pregnancy, 2- examination findings and 3- examination findings and 3- -hCG level as well as its rate of -hCG level as well as its rate of disappearance. If tissues have been passed, this should be disappearance. If tissues have been passed, this should be examined microscopically for chorionic villi. When examined microscopically for chorionic villi. When -hCG level -hCG level exceeds 1000 iu/l, intrauterine pregnancy would be visible by exceeds 1000 iu/l, intrauterine pregnancy would be visible by TVS (5000 iu/l for TAS). TVS (5000 iu/l for TAS). -hCG level is the key for management. -hCG level is the key for management.

A- A- -hCG <1000 iu/l: All the 3 possibilities are probable. If there are -hCG <1000 iu/l: All the 3 possibilities are probable. If there are no risk factors for ectopic pregnancy and no peritonism, review no risk factors for ectopic pregnancy and no peritonism, review after 48 hours by TVS and after 48 hours by TVS and -hCG. The absolute level of -hCG. The absolute level of -hCG -hCG (1000IU/L) should be relied upon rather than the rate of rise in (1000IU/L) should be relied upon rather than the rate of rise in --hCG level. Some ectopic pregnancies (13%) show normal rate of hCG level. Some ectopic pregnancies (13%) show normal rate of -hCG rise. Some normal pregnancies (15%) show slow rate of -hCG rise. Some normal pregnancies (15%) show slow rate of --hCG rise. (Between the 2nd & 4th post-ovulation weeks the level hCG rise. (Between the 2nd & 4th post-ovulation weeks the level of of -hCG doubles every 48 hours; ectopic pregnancy and -hCG doubles every 48 hours; ectopic pregnancy and abortion shows <66% rise). abortion shows <66% rise).

B- B- -hCG -hCG 1000 IU/L, only ectopic pregnancy or complete abortion 1000 IU/L, only ectopic pregnancy or complete abortion are possible. Laparoscopy can be considered or selectively with are possible. Laparoscopy can be considered or selectively with review in 48 hours. Complete abortion can be confirmed by a review in 48 hours. Complete abortion can be confirmed by a --hCG fall to 20% by 48 hours. History may assist decision-making. hCG fall to 20% by 48 hours. History may assist decision-making.

Regarding the disappearance rate of hCG: if it is less than 1.4 days, Regarding the disappearance rate of hCG: if it is less than 1.4 days, the most likely diagnosis is miscarriage. If it is greater than 7 the most likely diagnosis is miscarriage. If it is greater than 7 days, the case is almost always ectopic pregnancy. days, the case is almost always ectopic pregnancy.

# # Suspected trophoblastic disease.Suspected trophoblastic disease.

Thank youThank you