Non-Interpretive SkillsIntroduction to Pelvic and Obstetric Ultrasound

Before You Begin

This module is intended primarily for clinical medical students or interns intending to learn or review non-interpretive radiology skills.

Please note that while not integral, this module series assumes some familiarity with basic imaging techniques and interpretive skills. If you wish to learn or review these concepts, please see our “Interpretive Skills” module series.

If material is repeated from another module, it will be outlined as this text is so that you are aware

Objectives

• Explain the advantages of transvaginal ultrasonography compared to a transabdominal pelvic ultrasound

• Construct the appropriate imaging algorithm for: female pelvic pain, vaginal bleeding, suspected ectopic pregnancy

• Estimate the accuracy of ultrasound for pregnancy dating

• Schedule fetal ultrasounds at the appropriate diagnostic intervals

• Describe the limitations of ultrasound for prenatal diagnosis

Outline

• Imaging indications

• Techniques for pelvic imaging

• Pelvic ultrasound

• Premenopausal

• Postmenopausal

• Obstetrical ultrasound• First trimester sonogram • Second trimester sonogram

• Review

1. Ultrasound

2. MRI

3. CT

4. X-ray

Teaching point:US is the first line modality for pelvic imaging

Types of Pelvic Imaging

3 Main Category of Patients

1. Premenopausal2. Postmenopausal3. Pregnant

Indications for Pelvic Ultrasound(2014 AIUM Guidelines)

AIUM: American Institute of Ultrasound in Medicine

• Pelvic Pain• Pelvic Masses• Endocrine abnormalities, including PCOS• Dysmenorrhea (painful menses) or menorrhagia• Amenorrhea• Delayed menses• Evaluation of infertility patients• Limited physical exam• Pelvic Infection• Pelvic abnormality on different imaging modality• Follow-up previous finding• Congenital uterine and lower genital tract abnormalities• IUD location• Screening high-risk patients • Pre or postoperative evaluations

Teaching point:Clinical history is important to help narrow diagnosis.

Ultrasound Approaches

Ultrasound TechniqueLongitudinal View

UT

CX

CX

UT

* Deferred if virgin

RIGHT LEFT

Ultrasound TechniqueTransverse View

Normal ovaries and adnexa

It varies with age!

Premenopausal Physiological folliclesAverage size 9-15 ml

Postmenopausal Punctate echo fociAverage size 2-6 ml

Menstrual cycle variation of ovaries

It varies with age!

2 Phases of Menstrual Cycle

1. EstrogenDay 1-9: Small <5 mm folliclesDay 10: Dominant follicle emergesDay 14: Mature ovum with cumulus oophorus

2. Progesterone:Day 14 Midcycle LH surge: Egg rupture and release creates corpus luteumDay 14-27: Remainder of follicles involute

Estrogen Progesterone

Menstrual cycle variation of uterus

It varies with age!Day 14 Ovulation

Teaching point:Best time to obtain pelvic ultrasound is immediately post menses

Pitfall: Imaging at the Wrong PhaseSecretory phase, h/o heavy bleeding

Proliferative phase Sonohysterogram

Teaching point:Best time to obtain pelvic ultrasound is immediately post menses

Limitations of Pelvic US

Transabdominal :• Empty bladder• Body habitus• Bowel gas

Transvaginal:• Neutral lie of the uterus• Bowel gas• Fibroids

Adnexal Masses

Benign Ovarian Masses

Hemorrhagic Cyst Corpus LuteumSimple Cyst

Levine D, Brown DL, Andreotti RF et-al. Radiology. 2010;256 (3): 943-54Corpus luteum: Case courtesy of Dr Matt A. Morgan, Radiopaedia.org, rID: 42531

Endometrioma Dermoid

Benign Extraovarian Masses

Peritoneal Inclusion CystHydrosalpinx

Levine D, Brown DL, Andreotti RF et-al. Radiology. 2010;256 (3): 943-54

Paraovarian cyst

Management of Benign Ovarian masses

Features concerning for Ovarian Neoplasm

Levine D, Brown DL, Andreotti RF et-al. Radiology. 2010;256 (3): 943-54

Thick Septations (> 3mm) Mural Nodule w/ flow Solid

Abnormal Bleeding

Committee Opinion No. 557 ACOG April 2013

Abnormal Uterine Bleeding

Ultrasound Findings for Menorrhagia

Endometrial Polyps Leiomyomas/FibroidsEndometrial Polyps Adenomyosis

Hyperplastic overgrowthsof endometrial glands and

stroma around vascular core

Benign smooth muscle tumor located in the myometrium

Ectopic endometrial glands and stroma in the

myometrium

Teaching Point:Premenopausal causes for abnormal uterine bleeding are most often benign

Ultrasound Findings for Menorrhagia

US

MRI

Endometrial Polyps Leiomyomas/FibroidsEndometrial Polyps Adenomyosis

Abnormal Bleeding:Malpositioned IUD

Leiomyomas/Fibroids

Benign smooth muscle tumor located in the myometrium

Normal Myometrial penetrationand

Inferiorly positioned

Wildemeersch D, Hasskamp T, Goldstuck ND (2016).. Clin Obstet Gynecol Reprod Med 2

Postmenopausal Bleeding

Causes

Atrophy Polyp Poliferative/Secretory Fibroid Hyperplasia

Atrophy (31%)

Polyp (37%)Atrophy: Endometrial bilayer thickness 4-5 mm or less

Endometrial carcinoma: 7%

Goldstein RB, Bree RL, Benson CB, et al. J Ultrasound Med. 2001 Oct;20(10):1025-36.Van den Bosch, Ameye, Van Schoubroeck, et al. Facts Views Vis Obgyn. 2015; 7(1): 17–24.

ET >20 mm

Teaching Point:Thin postmenopausal endometrium virtually excludes endometrial cancer

SRU Management:Postmenopausal Bleeding

Goldstein RB, Bree RL, Benson CB, et al. J Ultrasound Med. 2001 Oct;20(10):1025-36.

Pelvic Pain

Ultrasound for Acute Pelvic Pain

Not Pregnant

Acute Pelvic Pain

B-Hcg?

PID

Torsion

Appendicitis

Ruptured Cyst

Teaching point: Must obtain pregnancy test prior to ordering a pelvic US

Pregnant

SubchorionicHemorrhage

Pregnancy Failure

Ectopic

Appendicitis

Acute Pelvic Pain in Non-Pregnant Pt

Not Pregnant

PID

Torsion

Appendicitis

Ruptured Cyst

Nl Rt Ov6 year old with LLQ pain, nausea, and vomiting

Torsion of Lt Ov

25 y w fever, CMT, vaginal discharge

TOA Pyosalpinx

Ruptured hemorrhagic cyst

Appendicitis

Which image is a surgical emergency?

PCOS Torsion

Chang H, Bhatt S, Dogra V et-al. Radiographics. Sep 2008, Vol. 28:1355–1368Callen, A.L., Illangasekare, T. & Poder, L. Emerg Radiol (2017) 24: 215.

Ovarian Hyperstimulation

Irregular Menses Nausea, Pelvic Pain Infertility treatment

Teaching point: Clinical history is crucial to accurate diagnosis

Massive Ovarian Edema

Mild painEdema reactive to

Subacute appendicitis

Acute Pelvic Pain in Pregnant Pt

Pregnant

SubchorionicHemorrhage

Pregnancy Failure

Ectopic

Appendicitis

“Tubal Ring” Sign- Ectopic Pregnancy

Yegul and Filly. J. Ultrasound Med 2009; 28:1331-1335.Rodgers SK, Chang C, DeBardeleben JT, and Horrow MHRadioGraphics 2015 35:7, 2135-2148

Pregnancy Failure:Expanded amnionNo cardiac activity in CRL >7 mm

Large subchorionic hematoma

Pregnant Patient

Types of OB US

FIRST TRIMESTER

“THE BASICS”

- Is pregnancy viable?- Where is it?

SECOND TRIMESTER/THIRD TRIMESTER

“PREPARING FOR DELIVERY”

- Is there contraindication to NSVD?- Fetal anomalies?

First Trimester Sonogram (0-13 wks)

• Goals: • Location of implantation: Intrauterine vs. ectopic

• Dating: If last menstrual period (LMP) uncertain

• Viability: Reaching appropriate milestones, +cardiac motion

• Complications: subchorionic hematoma, ovarian masses

• Genetic Screening: Measurement of nuchal translucency (11-13 wks)

• Components:

Embryonic: Include GS, YS, embryo, measurements, cardiac activity, number, anatomy, nuchal

Maternal: Uterus, adnexae, cul-de-sac

• For multiple gestations:

• Establish FETAL NUMBER

• Establish TYPE of twin pregnancy

TV US Landmark Timeline

Radiology 1986; 161:463-467Bradley et al. Radiology 1982; 143:223-226

LMP

2 wks Menstrual Age: Fertilization

2+ wks Decidual (Endometrial) Changes

3.5-4.5 wks Blastocyst implants into decidua: “Intradecidual Sign”

5 wks Empty gestational sac (mean diameter 10 mm)

Radiology 1986; 161:463-467Bradley et al. Radiology 1982; 143:223-226

J Ultrasound Med 2012; 31:87-95

5w 4d Gestational sac with yolk sac visible

6 wks Gestational sac (MSD 16mm) and yolk sac with adj heart beat and small embryo 3mm

6.7 wks Amnion surrounds embryo

8 wks Embryo with CRL 16 mm with separate amniotic sac and coelomic cavity with yolk sac. Fetal body movements visible, HR 175 bpm

YS Embryo w/HM Amnion

TV US Landmark Timeline

First Trimester Sonogram +Beta HCG, No embryo

Pregnancy of Unknown Location

Appropriate rise in B-hcgFollow-up Ultrasound in 8 days

Next Step in Management?

Teaching point: Follow Beta Curve and repeat ultrasound if IUP not confirmed. Ddx: Normal, Abnormal, or Ectopic Pregnancy

Doubilet et al. NEJM Oct 2013;369:1443-1451.

Transvaginal US for diagnosis –TA US CRL >15mm and w/o heartbeat

If Suspicious –Can get US in 7-10 days

First Trimester Sonogram Findings diagnostic for Pregnancy Failure

Mean GS diameter >25 mm, no embryo

CRL >/= 7 mm, no heart beat

Doubilet et al. NEJM Oct 2013;369:1443-1451

Other diagnostic findings:No embryo with heartbeat, 1. >/= 2 weeks after a scan with GS, no YSOr2. >/= 11 days after scan with GS and YS

First Trimester Sonogram Findings suspicious for Pregnancy Failure

Empty amnion Expanded amnion

Remember:Amnion normallySeen after +Cardiac motion

Other suspicious findings:1. CRL < 7mm without heart beat (HB)2. MSD 16-24 mm and no embryo3. Absence of embryo w/HB 7-13 days after a scan with GS, no YS4. Absence of embryo w/HB 7-10 days after a scan with GS and YS5. Enlarged yolk sac (>7mm)6. Small gestational sac relative to embryo (<5 mm diff between GS and CRL)

“Bunch of grapes” =

Gestational trophoblastic disease

Molar pregnancy

First Trimester Sonogram +Beta HCG, No embryo

First Trimester Sonogram Ectopic Pregnancy

• Locations: Majority are Tubal 95%Cesarean section Scar Heterotopic (ectopic and intrauterine)

• Present with Vaginal bleeding and Pain

• Risk Factors: Abnormal fallopian tube: PID, prior tubal ligationH/O prior ectopic pregnancyIUDH/O C-sectionFertility Treatment

Ectopic Pregnancy

Determine type of multiple in First Tri US

MonozygoticBrown sisters

of San Francisco

DizygoticScarlett & Hunter

Johansson

(*some monozygotics can be Di/Di)

ConjoinedChang & Eng Bunker

“Siamese Twins”

Chorions = # placentasAmnions = # yolk sacs

Teaching point: Determine type of twin gestation in the first trimesters as management is quite different. May not be able to distinguish later in gestation

Second Trimester Ultrasound(14-26 weeks)

• Routinely done at about 18-22 weeks

• Level 1 and 2

• Level 1: Basic screening

• Level 2: Targeted, High Risk

• Limited

Components1. Fetal presentation

2. Fetal number

3. Cardiac activity

4. Amniotic Fluid Volume

5. Gestational age assessmnt

6. Fetal Weight est

7. Fetal anatomy

8. Placental and cord

9. Maternal anatomy, incl cervix

Fetal Presentation

Vertex (cephalic presentation)

Head located above Cx

Cervix

Fetal Head

Cervical Length

Closed Cervical length

Less than 24 weeks: >/= 2.5 cm

Abnormal: Funneled and Short

Placenta Location

Posterior Placenta

Concerning: Placenta Previa

Complete Previa

Cx

• Placenta overlies internal cervical os

• Increased bleeding risk• C-section delivery at

36 w – 37w6d

Placental Cord Insertion & Placental Types

Placenta

Cord Insertions

Vasa Previa

Bilobed Placenta Succenturiate Lobe

Teaching point: Screen for Vasa Previa due to high risk of bleeding

Amniotic Fluid Volume• Qualitative vs Quantitative

• Qualitative: Subjective

• Quantitative: 1. Amniotic fluid Index

Sum 4 quadrantsNormal 8-24 cmOligohydramnios <5 cmPolyhydramnios >24 cm

2. Deepest vertical pocket (DVP)Normal 2-8 cmOligohydramnios <2 cmPolyhydramnios >8 cm

Reddy UM, Abuhamad AZ, Levine D, et al. Obstet Gynecol. 2014;123(5):1070.

Abnormal Amniotic Fluid Volume

OligohydramniosNormal

DVP

Polyhydramnios

Gestational Age/Fetal BiometryBiparietal Diameter : Head Circumference

Abdominal Circumference Femur Length

Estimated Fetal Weight

Fetal Anatomy

Head, face, and neck• Midline Falx• Cavum Septum Pellucidi• Lateral Ventricles• Choroid plexus• Cerebellum• Cisterna Magna• Nuchal thickness• Upper Lip

Chest• Four Chamber Heart• Outflow Tracts

Abdomen• Stomach• Kidneys• Urinary bladder• Abdominal cord insertion• Umbilical cord vessel

number

Spine

Extremities

Genitalia

Fetal Anatomy

Head, face, and neck• Midline Falx• Cavum Septum Pellucidi• Lateral Ventricles• Choroid plexus• Cerebellum• Cisterna Magna• Nuchal thickness• Upper Lip

Fetal Anatomy

Chest• Four Chamber Heart• Outflow Tracts

RVOT

LVOT

Fetal Anatomy

Abdomen• Stomach• Kidneys• Urinary bladder• Umbilical cord vessel

number• Abdominal cord insertion

Fetal Anatomy

Spine

Extremities

Genitalia

Fetal Anomalies

Cleft Lip

Myelomeningocele

Anencephaly

Gastroschisis

Questions

Question 1

The best first imaging test for a pelvic mass in a female patients is:

a) MRI

b) CT

c) Ultrasound

d) PET scan

The best first imaging test for a pelvic mass in a female patients is:

a) MRI

b) CT

c) Ultrasound

d) PET scan

Question 1

A patient presents with first trimester bleeding. What ultrasound finding would be reassuring for a potentially viable pregnancy?

a) An adnexal mass

b) Gestational sac with embryo within the uterus

c) Normal uterus without a gestational sac or embryo

d) Free fluid in the pelvis

Question 2

A patient presents with first trimester bleeding. What ultrasound finding would be reassuring for a potentially viable pregnancy?

a) An adnexal mass

b) Gestational sac with embryo within the uterus

c) Normal uterus without a gestational sac or embryo

d) Free fluid in the pelvis

Question 2

For a twin pregnancy, when is ultrasound most accurate for determining the chorionicity and amnionicity of the pregnancy?

a) Second trimester

b) First trimester

c) It makes no difference, measurement is easy and accurate at any point in the pregnancy

d) Right before delivery

Question 3

For a twin pregnancy, when is ultrasound most accurate for determining the chorionicity and amnionicity of the pregnancy?

a) Second trimester

b) First trimester

c) It makes no difference, measurement is easy and accurate at any point in the pregnancy

d) Right before delivery

Question 3

Which of the following fetal assessments is commonly performed on a first trimester ultrasound?

a) Sonographic age

b) Fetal anatomy

c) Amniotic fluid volume

d) Placental position

Question 4

Which of the following fetal assessments is commonly performed on a first trimester ultrasound?

a) Sonographic age

b) Fetal anatomy

c) Amniotic fluid volume

d) Placental position

Question 4

Which of the following is most important in evaluating whether the thickness of the endometrium is abnormal?

a) Parity

b) Phase of menstrual cycle

c) History of C section

d) Presence of fibroids

Question 5

Which of the following is most important in evaluating whether the thickness of the endometrium is abnormal?

a) Parity

b) Phase of menstrual cycle

c) History of C section

d) Presence of fibroids

Question 5

END