Saturday, April 13, 2013

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)

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