Request  Card  Task    ANSWERS  

Medical  Student  Workbook  

Author:  Dr  Sam  Leach,  SpR  

 

Case  1  

•  What  differential  diagnoses  are  most  likely?  

•  Which  investigation  is  most  appropriate?  

Case  1  

•  The  most  likely  diagnosis  here  is  renal  colic  +/-­‐  ureteric  

obstruction.  

–  Haematuria  

–  Loin  to  groin  pain  –  Bloods  may  indicate  dehydration  as  a  cause.  

•  Other  differentials:  

–  Appendicitis  –  but  you  would  expect  some  guarding  

–  Strangulated  hernia  –  you  may  find  this  on  examination.  

Case  1  

•  Most  appropriate  investigation  is  CT  KUB:  

– Reliably  diagnose  renal  calculi  

–  Evaluates  ureter  and  kidney  for  signs  of  obstruction.  

– May  provide  alternative  diagnosis  if  no  renal  calculi  

present  

– Non-­‐contrast  so  can  be  performed  safely  with  

abnormal  renal  function  

Case  1  

             CT  KUB  with  renal  pelvis  and  proximal  ureteric  dilatation  (red  arrow)  

secondary  to    obstruction  by  calculus  with  associated  perinephric  stranding  

(white  arrows)  

Case  1  •  Other  investigations  you  may  have  considered:  

–  AXR  –  may  reveal  calculus  but  less  reliable  than  CT  and  

will  not  show  ureteric  obstruction  

–  USS  abdomen  –  would  be  able  to  evaluate  obstruction  if  

progression  to  hydronephrosis  but  would  not  be  able  to  

diagnose  number/  size/  location  of  all  calculi  

–  IVU  –  still  used  as  an  alternative  to  CT  KUB  in  some  

hospitals,  however  less  reliable  at  finding  calculi,  time-­‐

consuming  and  has  the  disadvantage  of  using  iodinated  

contrast.  

Case  2  

•  What  differential  diagnoses  are  most  likely?  

•  Which  investigation  is  most  appropriate?  

Case  2  •  The  most  likely  diagnosis  here  is  cauda  equina  syndrome  –  with  

likely  causes  being  either  malignancy  from  previous  breast  cancer  

or  disc  prolapse.  

–  Bilateral  leg  weakness  and  pain  –  often  asymmetrical  

–  Saddle  anaesthesia  

–  Urinary  retention/sphincter  disturbance  

•  Differential  diagnoses  

–  MS,  transverse  myelitis  

–  Traumatic  cord  transection  –  unlikely  as  no  immediate  symptoms  

Case  2  

•  Most  appropriate  investigation  here  is    MRI  spine  

–  Only  modality  to  accurately  visualise  nerve  roots  and  

cauda  equina  

– Will  be  able  to  characterise  cause  of  nerve  root  

compression  

–  Allows  planning  of  surgery  

–  No  ionising  radiation  

– Will  be  able  to  identify  other  causes  of  these  symptoms  

Case  2  

Compression  of  the  conus/cauda  equina  by  collapse  of  T12  (red  arrow)  

secondary  to  bone  metastasis.  Arrowhead  indicates  deviation  of  the  cauda  

equina  rootlets.  Curved  arrow  shows  occlusion  of  spinal  canal  by  displaced,  

abnormal  bone  

Axial  T2   Axial  T2   Sagittal  T2  

Case  2  •  Other  investigations  you  may  have  considered:  

–  Spinal  X-­‐ray  –  may  indicate  fracture  or  intervertebral  

narrowing  but  won’t  identify  points  or  cause  of    

–  Pelvic  x-­‐ray  –  may  identify  pelvic  fracture  or  other  trauma  

but  again  not  useful  in  identifying  nerve  root  damage  or  

cauda  equina.  

–  CT  –  best  modality  for  characterising  the  configuration  of  

fractures  and  may  show  metastatic  process  but  not  

usually  able  to  accurately  identify  cord  compression.  

Case  3  

•  What  differential  diagnoses  are  most  likely?  

•  Which  investigation  is  most  appropriate?  

•  What  problem  might  this  investigation  pose  in  

this  patient?  

Case  3  •  The  most  likely  diagnosis  here  is  pulmonary  embolus  

which  may  well  be  massive  given  that  the  patient  has  

unstable  BP  

–  Pleuritic  chest  pain  –  Hypoxic  on  high  O2  

–  Immobility  with  long  bone  fracture  

•  Differential  diagnoses  –  Pneumothorax  –  less  likely  with  normal  respiratory  

examination  

–  Pulmonary  oedema  –  less  likely  with  normal  examination  

Case  3  

•  Most  appropriate  investigation  here  is  CT  

pulmonary  angiogram:  

– Quick  imaging  technique  

– Able  to  identify  amount/  location  of  thrombus  

– Would  also  help  rule  out  other  differentials  

– Can  indicate  right  heart  strain  

Case  3  

CT  pulmonary  angiogram  demonstrating  saddle  embolus,  seen  as  

a  dark  filling  defect,  at  division  of  pulmonary  trunk    (red  arrow)  

Case  3  

•  Other  investigations  you  may  have  considered:  

–  CXR  –  May  rule  out  differentials  but  unable  to  reliably  diagnose  

PE.  With  lack  of  chest  signs  and  just  rib  fractures  on  admission  

CXR  would  likely  be  reasonable  to  move  straight  to  CTPA.  

–  V/Q  (Ventilation/  Perfusion)  scan  –  slow  investigation  so  not  

appropriate  with  acutely  unwell  patient  and  less  reliable.  

–  Pulmonary  angiogram  –  complex  procedure,  no  longer  

performed  in  most  hospitals  and  would  not  rule  out  

differentials.  

Case  3  

•  What  problem  might  this  investigation  pose?:  

–  CTPA  is  a  contrast  examination.  

–  This  patient  has  a  history  of  diabetes  which  predisposes  to  

renal  disease  

– We  have  no  recent  results  for  eGFR  

–  Ideally  we  would  have  a  baseline  level  for  this  patient  from  

previous  blood  results  

–  eGFR  should  be  at  >30  for  contrast  examinations  

Case  4  

•  What  differential  diagnoses  are  most  likely?  

•  Which  investigation  is  most  appropriate?  

Case  4  •  The  most  likely  diagnosis  here  is  an  acute  subdural  haematoma  

(the  hypoxia  may  be  due  to  inability  to  protect  their  airway  or  

atelectasis  from  a  long  lie).  

–  Evidence  of  fall  and  head  injury  

–  Deranged  INR  

–  Reduced  GCS  

•  Possible  differentials  might  include:  

–  Haemorrhagic  stroke  –  though  no  clear  evidence  of  focal  neurology  

–  Hypoglycaemia  

–  Post-­‐ictal    

Case  4  

 CT  head  showing  acute  

subdural  haematoma  (red  

arrow)  with  mass  effect  and  

midline  shift  

Case  4  

•  Other  investigations  you  may  have  considered  might  be:  

–  Skull  x-­‐ray  –  would  not  be  able  to  characterise  haemorrhage  or  

usually  identify  it.  Largely  redundant  if  CT  head  is  appropriate  

as  skull  can  be  visualised  on  bone  windows  for  fractures  

–  MRI  –  Accurate  in  identifying  haemorrhage  but  not  as  quick  as  

CT  and  therefore  less  appropriate  in  this  situation.  Would  be  

useful  if  no  abnormality  found  on  CT  as  can  identify  

parenchymal  pathology  more  effectively.  

Long  case  Fill  out  the  request  card  for  this  case  then  

read  through  the  example  card  and  

discussion  

Case  History  

Fill  out  the  request  form  for  this  patient  with  the  

most  appropriate  investigation,  including  

differential  diagnoses  

Example  request  card  

St  St  St  Elsewhere  NHS  Trustospital  NHS  Trust  

Discussion  There  are  several  other  less  likely  possible  differentials  which  could  also  be  

considered:  

•  Pyelonephritis  

•  Early  appendicitis  

•  Pancreatitis  

•  Reflux  disease  +/-­‐  peptic  or  duodenal  ulcer  –  not  normally  investigated  in  acute  

setting  unless  perforation/  hematemesis  

 

 Perforation  of  ulcer  is  unlikely  given  the  normality  of  other  observations,  the  lack  

of  generalised  guarding  and  the  lack  of  hematemesis  but  should  always  be  

considered  

Discussion  

Regarding  the  other  findings  from  the  history:  

•  Mild  tachycardia  is  most  likely  to  be  related  to  pain  

•  Amylase  rise  is  small  and  can  be  associated  with  cholecystitis  

•  Gamma  GT  is  elevated  but  may  reflect  a  high  alcohol  intake  –  the  

other  LFTs  are  normal  

•  Decreased  eGFR  is  most  likely  to  be  associated  with  dehydration  –  

the  patient  has  been  vomiting  and  passed  lots  of  urine,  most  likely  

related  to  alcohol  intake  

 

Discussion  The  most  appropriate  investigation  is  ultrasound:  

•  Reliable  at  identifying  gallstones  and  cholecystitis  

•  No  ionising  radiation  

•  Can  also  assess  liver  and  common  bile  duct  at  same  time  for  

complications  of  gallstone  disease  

•  Can  attempt  to  visualise  appendix  and  check  for  inflammation,  as  

well  as  kidneys  for  pyelonephritis  

•  Can  demonstrate  free  fluid  in  the  abdomen  indicating  other  

pathology  and  possibly  need  for  further  investigation  

 

Discussion  

             Ultrasound  of  acute  cholecystitis  with  gallstones  (red  arrow)  and  wall  

thickening  (yellow  arrows  indicate  wall  thickness  greater  than  3-­‐4mm).  

Discussion  Other  investigations  you  may  have  considered:  

•  Erect  Chest  x-­‐ray  –  though  perforation  does  not  seem  likely,  this  may  be  

acceptable  to  rule  out  perforation  

–  As  it  is  ionising  radiation  though  it  would  be  necessary  in  most  situations  to  rule  out  

pregnancy  first  

–  This  modality  would  be  unlikely  to  give  you  any  further  information  about  the  cause  of  the  

symptoms  

•  Abdominal  X-­‐ray  –  high  dose  of  radiation  that  is  unlikely  to  give  further  

information  

–  Gallstones  unlikely  to  be  visualised  -­‐  >90%  are  radiolucent  

–  Erect  chest  x-­‐ray  more  useful  and  lower  dose  to  rule  out  perforation  

–  No  indication  of  obstruction  in  the  history  

Discussion  •  Abdominal  CT  –  Will  be  able  to  give  most  information  and  identify  

most  of  these  differentials  

–  High  dose  and  not  necessary  in  a  stable  patient,  with  a  diagnosis  

which  could  be  confirmed  with  US  

–  If  pancreatitis  is  strongly  suspected  then  may  be  used  to  look  for  

complications  

–  May  be  necessary  if  patient  deteriorates  or  becomes  unstable.  

•  Non-­‐radiological  –  endoscopy  

–  Can  be  used  to  look  for  ulcers  and  evidence  of  reflux  but  would  not  

exclude  or  identify  differential  diagnoses  

The  End