Scan technique i

First trimester

Indications

• Bleeding after a POA
• Pain during pregnancy
• Pregnancy complicated by fibroid or ovarian cyst

 

Preparation
Scans are performed though the full bladder using a 5 MHtz curvilinear probe.

Indications for first trimester sonography 

• Localization of the GS –Intra uterine or Ectopic pregnancy
• Identification of foetal viability
• Anovular gestation
• Estimation of POG
• Assessment of multiple pregnancy, number of embryos chorionicity & amniocity

5-12 weeks

• Well-defined gestational sac/sacs (well defined hypo echoic rounded structure) with fetal yolk sac (separate hypo echoic area within the GS outlined by an echogenic ring) & foetal echoes (oval shaped echogenic area) are located in the fundus of the uterus.
• Yolk sac identified when the mean sac diameter is > than 8mm.

8-10 weeks

• Heart pulsations identified during by trans vesicle scan fetal cardiac pulsations should be present when fetal CRL is > 7mm

Defective early pregnancy

• Abnormal GS size (Growth failure growth rate of the sac is 1.1mm /day, blighted ovum - mean gestational sac > 20mm with out yolk sac & fetal echoes)
• Absent yolk sac & absent or in compatible fetal echoes
• Ill-defined or deformed GS & low implantation
• Ill defined placenta & /or disorganized intra uterine
• Echoes (Missed abortion or H mole)
• Double or triple sacs like structures with in the uterus.
• GS outside the uterus (Ectopic pregnancy)

Ectopic pregnancy

 

Following are sonographic features of ectopic pregnancy.

Specific features

• Live embryo outside the uterus

Non-specific features (Correlate with β- hCG)

• Empty uterus
• Pseudo gestational sac of ectopic pregnancy
• Particulate ascites
• Adenexal mass
• Ectopic tubal ring

Non-supportive features

• Negative β- hCG
• Live intrauterine pregnancy

Report

Should consist the following.

1.GS

• Whether the GS is intrauterine or extra uterine should be documented.
• If intra uterine site of the GS whether it is in the fundus, body or cervical region of the uterus, number of sacs, & whether foetal echoes are present or absent should be documented.
• GS size should be measured & documented. Whether heart pulsations & movements present or absent should be documented.

2.Adenexa & pouch of Douglas

• Cysts, masses, free fluid or other abnormalities should be looked for & documented.

3.Conclusion

• Normal intrauterine pregnancy
• Abnormal intrauterine pregnancy
• Ectopic pregnancy (ruptured or un ruptured)