iBSc: Question 8

By Alan McLeod

Getting the best marks

Read the whole question – a latter section may give you a

clue about an earlier one.

To see how many points you need look at the marks

allocated – for example a 3 point question is generally looking for 3 salient points

If giving a list answer put the best answers first – examiners will not usually mark answers too

far down a list

Always write something – it may get you part of a mark and is anonymised so

no one will think you are stupid!

If you genuinely have no clue then re-write the question to see if this sparks

some ideas.

If not then move on and come back at the end. And remember – always

write something.

Good luck!

Question 8

Andrea, a 19 year old girl presents with right iliac fossa pain.

Q8.1• List 3 differentials (3)

Question 8

Your SHO tells you not to forget to

palpate McBurneys point in the exam.

Q8.2• Where is McBurneys

point? (2)

Q8.3• What is it’s

significance? (1)

Question 7

Andrea has missed her last period.

Q8.4• Illustrate the hormonal

changes of the menstrual cycle showing the four main hormones (8)

Question 7

A pregnancy test is performed

Q8.5• What is the molecule

detected by this test (3)

Q8.6• What is this molecules

physiological purpose? (1)

Question 7

The test is positive - it is a reliable test

with a good sensitivity and

specificity.

Q8.7• Define the statistical

terms sensitivity and specificity (2+2)

Question 8

Ultrasound shows no foetus in the uterus

and an ectopic pregnancy is diagnosed

Q8.8• What is the commonest

site for an ectopic pregnancy to implant? (1)

Q8.9• List two other sites of

ectopic implant (2)

Question 8

After successful treatment, Andrea

reveals she is sexually active with

multiple partners and does not use

contraception.

Q8.10• Compare the

combined oral contraceptive pill and the condom for mode of action, advantages and disadvantages (6)

Question 8

Andrea’s chaotic lifestyle lead you to believe that a long term contraceptive

option may be best.

Q8.11• List a long term mode

of contraception (lasts at least 3 months) and its mode of operation. (2)

The Answers

View these on ‘note view’ rather than on full screen – additional

notes are provided for some slides

Abdo Pain?

I Infectious/inflammatory Appendicitis, gastroenteritis, food poisoning

G Genetic / Ideopathic

E Endrocrine Diabetic ketoacidosis (mainly in children)

T Trauma

V Vascular / blood

I Iatrogenic / ingested Surgical adhesions

N Neoplastic

O Organs / other LOTS and LOTs…

Abdominal Organs

Right Hypochondrial:LiverGall bladderColon (hepatic flexure)

Epigastric:StomachDuodenum r

Colon (transverse)Pancreas r

Aorta R

Left Hypochondrial:StomachSpleen Pancreas (tail) r

Colon (splenic flexure)

Right Lumbar:Colon (ascending) r

Kidney R

Umbilical:Small bowelColon (transverse)Aortic bifurcation R

Left Lumbar:Colon (descending) r

Kidney R

Right Iliac FossaCaecumAppendixOvary / ovarian tubeUreter

Suprapubic:Rectum Urinary bladder R

Left Iliac FossaColon (descending)Colon (sigmoid)Ovary / ovarian tubeUreter

Abdominal Organs

Embryology Arterial supply Visceral pain in

Red Foregut Coeliac trunk Epigastrium

Green Midgut superior mesenteric Umbilical quadr

Blue Hindgut Inferior Mesenteric Suprapubic quadr.

Junction Points:

Foregut becomes Midgut: Ampulla of Vater – halfway along second section of duodenum

Midgut becomes Hindgut: approximately at the splenic flexure

R= primary retroperitoneal structurer= secondary retroperitoneal structure

Right Iliac Fossa Pain

Gut Gynae Other Appendicitis Mesenteric

adenitis

Ectopic Pregnancy

Ovarian cyst torsion

Salpingitis Ureteric stone

McBurney’s Point

Umbilicus

Rt ASIS

Basis of Pregnancy Test

• Implanting embryo produces human chorionic gonadotrophin (hCG)

• This stabilises the corpus luteum allowing continued progesterone production and pregnancy to continue

• hCG has 2 chains – alpha and beta

• Pregnancy test detects the beta-chain of the hCG molecule.

• Levels peak at 9-11 weeks

• Detectable 14 days post ovulation in urine and 6-7 days in plasma

Menstrual Cycle

Menstruation

Follicular phase

• Reducing oestrogen and progesterone – reduction of neg feedback on pituitary

• Pituitary releases FSH/LH

Within the follicle

• LH + Thecal cells gives choleterol androgens

• FSH causes proliferation of granulosa cells

• FSH + Granulosa gives androgens oestrogens

Little Tiny Follicles Grow: LH + Thecal cells; FSH + Granulosa

Menstruation

• Follicular phase (cont…)

• Selection of dominant follicle – produces oestrogen

• Oestrogen levels rise until passing level for inducing positive feedback on LH

• FSH + oestrogen induce LH receptors

• LH receptor levels rise

• Luteinisation of follicle occurs– Progesterone produced

• Progesterone potentiates positive feedback of oestrogen

• LH Surge

Menstruation

Ovulation• Occurs 36 hours after

LH surge• Meiosis restarts within

the oocyte• Follicle wall breaks

down release of oocyte

Luteal phase• Corpus luteum

produces progesterone

• Induced by LH• Continued production

needed for pregnancy• LH levels falling…

Sensitivity and Specificity Or: The Spinning Snout Test

• SPPIN = Sp+P+In

If a test has a high • Specificity then a• Positive result rules

the diagnosis• In

• SNNOUT = Sn+N+Out

If a test has a high • Sensitivity then a• Negative result rules

the diagnosis• Out

Ectopic Pregnancy

Combined Oral Contraceptive

Effectiveness• Pearl index: 0.3 – 4

Main Mode of action• Suppress synthesis

and secretion of FSH and the mid-cycle surge of LH.

Other actions• Endometrium: Results

in inadequte proliferation and secretory phases – preventing implantation.

• Cervical mucus: inhibits sperm penetration

Combined Oral Contraceptive

Advantages• Usually results in pain-free,

moderate periods

• Less PID / ectopics

• Less ovarian / endometrial cancer

• Less iron defic anaemia

• Less benign breast disease

• Less symptoms of the menopause

• Fewer ovarian cysts

Disadvantages:• No STI protection• Breast tenderness• Nausea• Headaches• Leg cramps• Depression• Acne• Alopecia• Hirsutism• Weight gain

Condom

Advantages:• Protection from STI’s

e.g. Chlamidia, HIV. Limited protection against HPV.

• Easy to use.• Non-hormonal.• Available free from

family planning clinics and similar sites.

• Disadvantages:• Interfere with sex.• Allergy.• Can be damaged by

oil-based products e.g. baby oil, some thrush treatments.

Condom

Effectiveness:• Pearl index 2-15

dependent on care in useage.

Mode of action:• A physical barrier that

prevents entry of the sperm into the vagina or cervix. Barrier methods need to be put in place before genital contact as the pre-ejaculate contains sperm.

Long term contraception

Male sterilisation• Ads: Very low failure rate (0 – 0.05% over lifetime), does

not interfere with sex. Nothing to remember.• Disads: should be considered permanent, no protection

vs STIs

Female sterilisation• Ads: Does not interfere with sex. Nothing to remember.• Disads: Relatively high failure rate (0 – 0.5% over

lifetime) – recanalisation not uncommon. Should be considered permanent, no protection vs STIs

Long term contraception

Implanon device• Action: Slow release of a progestogen - inhibits

ovulation, thickens the cervical mucus, inhibiting the passage of sperm to the uterus, and thins the endometrium, preventing implantation.

• Ads: Virtually no failure chance, Lasts years, reversible• Disads: May cause Irregular bleed, acne, ‘wt gain’

Long term contraception

IUCD ‘coil’• Action: induces an inflammatory response in the uterus

which affects the viability of sperm and ova. Prevent fertilisation and implantation

• Ads: Low failure (Pearl index 0.2 - 1), reversible.• Disads: Often causes menorrhagia

The End

The slides here should allow you to mark your own work – remember 1 mark per

answer up to the maximum for the question. Multiply by 3 to get percentage points. I assume a 60% pass mark. Sorry but I am unable to give further advice on

answers due to time constraints.